Systems and methods for producing propylene

ABSTRACT

According to one embodiment described in this disclosure, a process for producing propylene may comprise at least partially metathesizing a first stream comprising at least about 10 wt. % butene to form a metathesis-reaction product, at least partially cracking the metathesis-reaction product to form a cracking-reaction product comprising propylene, and at least partially separating propylene from the cracking-reaction product to form a product stream comprising at least about 80 wt. % propylene.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/190,964 filed Jun. 23, 2016 which claims priority to U.S.Provisional Application Ser. No. 62/188,052 filed Jul. 2, 2015, and theentire disclosure of each are hereby incorporated by reference herein.

BACKGROUND Field

The present disclosure generally relates to processes and systems forproducing propylene, and more specifically, to processes and systems forproducing propylene from process streams comprising butene.

Technical Background

In recent years, there has been a dramatic increase in the demand forpropylene to feed the growing markets for polypropylene, propyleneoxide, and acrylic acid. Currently, most of the propylene producedworldwide is a byproduct from steam cracking units which primarilyproduce ethylene, or a by-product from FCC units which primarily producegasoline. These processes cannot respond adequately to a rapid increasein propylene demand.

Other propylene production processes contribute to the total propyleneproduction. Among these processes are propane dehydrogenation (PDH),metathesis reactions requiring both ethylene and butene, high severityFCC, olefins cracking, and methanol to olefins (MTO). However, propylenedemand has increased and propylene supply has not kept pace with thisincrease in demand.

Regarding the production of propylene by metathesis requiring ethyleneand butene, generally, a stoichiometric ratio of about 1 butene to 1ethylene is desirable for high product yield. However, in some cases,ethylene is not available, or is not available in great enoughquantities compared to butene supply. Therefore, such processesrequiring butene and ethylene may not be feasible due to lack ofethylene supply available for reaction. Accordingly, an ongoing needexists for a process for efficiently converting butene to propylene, andspecifically for efficiently converting butene to propylene without theneed for ethylene.

BRIEF SUMMARY

In accordance with one embodiment of the present disclosure, propylenemay be produced by a process comprising at least partially metathesizinga first stream comprising butene to form a metathesis-reaction product,at least partially cracking the metathesis-reaction product to produce acracking-reaction product comprising propylene, and at least partiallyseparating propylene from the cracking-reaction product to form aproduct stream comprising propylene.

In accordance with another embodiment of the present disclosure,propylene may be produced by a process comprising introducing a firststream comprising butene to a reactor, at least partially metathesizingthe first stream with a metathesis catalyst to form ametathesis-reaction product, at least partially cracking themetathesis-reaction product with the cracking catalyst to form acracking-reaction product, passing the cracking-reaction product out ofthe reactor in a cracking-reaction product stream, and at leastpartially separating propylene from the cracking-reaction product streamto form a product stream comprising propylene. The reactor may comprisea metathesis catalyst and a cracking catalyst, the metathesis catalystpositioned generally upstream of the cracking catalyst.

In accordance with yet another embodiment of the present disclosure,propylene may be produced by a process comprising introducing a firststream comprising butene to a first reactor, at least partiallymetathesizing the first stream in the first reactor to form ametathesis-reaction product, passing the metathesis-reaction product outof the first reactor in a metathesis-reaction product stream and into asecond reactor, at least partially cracking the metathesis-reactionproduct stream in the second reactor to form a cracking-reactionproduct, passing the cracking-reaction product out of the second reactorin a cracking-reaction product stream, and at least partially separatingpropylene from the cracking-reaction product stream to form a productstream comprising propylene. The first reactor may comprise a metathesiscatalyst and the second reactor may comprise a cracking catalyst. Atleast a portion of the butene in the cracking-reaction product streammay be recycled by at least partially separating butene thecracking-reaction product stream to form a recycle stream comprisingbutene, where the first stream is a mixture of the recycle stream and asystem inlet stream.

According to embodiments, metathesis catalysts may be utilized whichcomprises a mesoporous silica catalyst impregnated with metal oxide,where the mesoporous silica catalyst includes a pore size distributionof about 2.5 nm to about 40 nm and a total pore volume of at least about0.600 cm³/g. In another embodiment, a cracking catalyst may be utilizedwhich comprises a mordenite framework inverted (MFI) structured silicacatalyst, where the MFI structured silica catalyst includes totalacidity of 0.001 mmol/g to 0.1 mmol/g. In another embodiment, a crackingcatalyst may be utilized which comprises an amorphous mesoporous silicafoam impregnated with metal oxides, where the metathesis catalyst has apore size distribution of at least 3 nm to 40 nm and a total pore volumeof at least 0.700 cm³/g.

In accordance with yet another embodiment of the present disclosure,systems may be operable to perform the processes for producing propylenedescribed in this disclosure.

Additional features and advantages of the technology disclosed in thisdisclosure will be set forth in the detailed description which follows,and in part will be readily apparent to those skilled in the art fromthe description or recognized by practicing the technology as describedin this disclosure, including the detailed description which follows,the claims, as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is a generalized diagram of a butene conversion system comprisinga dual catalyst reactor, according to one or more embodiments describedin this disclosure;

FIG. 2 is a generalized diagram of a butene conversion system comprisinga dual catalyst reactor and a recycle stream, according to one or moreembodiments described in this disclosure;

FIG. 3 is a generalized diagram of a butene conversion system comprisingreactors in series, according to one or more embodiments described inthis disclosure;

FIG. 4 is a generalized diagram of a butene conversion system comprisingreactors in series and a recycle stream, according to one or moreembodiments described in this disclosure;

FIG. 5 depicts a bar graph displaying the product distribution in wt. %(weight percent) of the system of FIG. 1, according to one or moreembodiments described in this disclosure;

FIG. 6 depicts a bar graph displaying butene conversion (in wt. %) inthe system of FIG. 1, according to one or more embodiments described inthis disclosure;

FIG. 7 depicts a bar graph displaying the product distribution (in wt.%) of the system of FIG. 2, according to one or more embodimentsdescribed in this disclosure;

FIG. 8 depicts a bar graph displaying the product distribution (in wt.%) of the system of FIG. 3, according to one or more embodimentsdescribed in this disclosure;

FIG. 9 depicts a bar graph displaying the product distribution (in wt.%) of the system of FIG. 4, according to one or more embodimentsdescribed in this disclosure;

For the purpose of the simplified schematic illustrations anddescriptions of FIGS. 1-4, the numerous valves, temperature sensors,electronic controllers and the like that may be employed and well knownto those of ordinary skill in the art of certain refinery operations arenot included. Further, accompanying components that are in conventionalrefinery operations including catalytic conversion processes such as,for example, air supplies, catalyst hoppers, and flue gas handling arenot depicted. However, operational components, such as those describedin the present disclosure, may be added to the embodiments described inthis disclosure.

It should further be noted that arrows in the drawings refer to transferlines which may serve to transfer steams between two or more systemcomponents. Additionally, arrows that connect to system componentsdefine inlets or outlets in each given system component. The arrowdirection corresponds generally with the major direction of movement ofthe materials of the stream contained within the physical transfer linesignified by the arrow. Furthermore, arrows which do not connect two ormore system components signify a product stream which exits the depictedsystem or a system inlet stream which enters the depicted system.Product streams may be further processed in accompanying chemicalprocessing systems or may be commercialized as end products. Systeminlet streams may be streams transferred from accompanying chemicalprocessing systems or may be non-processed feedstock streams.

Reference will now be made in greater detail to various embodiments,some embodiments of which are illustrated in the accompanying drawings.Whenever possible, the same reference numerals will be used throughoutthe drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

Generally, described in this disclosure are various embodiments ofsystems and methods for converting butene into propylene. Generally, theconversion systems include system components which are operable to carryout a method where a stream comprising butene undergoes a metathesisreaction and a cracking reaction to form propylene. In some embodiments,the metathesis reaction may be followed by the cracking reaction, wherethe metathesis and cracking reactions may be carried out in separatereactors arranged in series or may be carried out in a single reactorcomprising multiple catalysts positioned in different sections of thereactor. Following the metathesis and cracking reactions, the productstream may be separated into multiple streams, where some streams mayoptionally be recycled back into the system. Following a downstreamseparation process, a product stream comprising at least about 80 wt. %propylene may be produced from the reaction products of the crackingreaction. The systems may operate with a single system inlet streamcomprising at least about 50 wt. % butenes, such as raffinate streamscreated from a naphtha cracking process. The systems generally do notrequire a system inlet comprising ethylene, and the process is fullyfunctional without ethylene supplied to the system.

As used in this disclosure, “transfer lines” may include pipes,conduits, channels, or other suitable physical transfer lines thatconnect by fluidic communication one or more system components to one ormore other system components. As used in this disclosure, a “systemcomponent” refers to any apparatus included in the system, such as, butnot limited to, separation units, reactors, heat transfer devices suchas heaters and heat exchangers, filters, impurities removal devices,combinations of each, and the like. A transfer line may generally carrya process stream between two or more system components. Generally, atransfer line may comprise multiple segments, where a “segment” of atransfer line includes one or more portions of a transfer line, suchthat a transfer line may comprise multiple transfer line segments.Generally, the chemical composition of a process stream in a particulartransfer line is similar or identical throughout the entire length ofthe transfer line. However, it should be appreciated that thetemperature, pressure, or other physical properties of a process streammay change through a transfer line, particularly in different transferline segments. Also, relatively minor compositional changes in a processstream may take place over the length of a transfer line, such as theremoval of an impurity. Also, sometimes the systems described in thisdisclosure are referred to as “butene conversion systems,” which refersto any system which at least partially converts butene into one or moreother chemical species. For example, in some embodiments, butene is atleast partially converted into propylene. As described in thisdisclosure, the butene conversion systems are suitable to processstreams comprising butene, including streams that are substantially freeof other alkenes (for example, ethylene, propene), into a productprocess stream comprising a significant amount of propylene. As used inthis disclosure, a stream or composition does “not substantiallycomprise” or “is substantially free” of a component when that componentis present in an amount of less than 0.1 wt. %.

As used in this disclosure, a “separation unit” refers to any separationdevice that at least partially separates one or more chemicals that aremixed in a process stream from one another. For example, a separationunit may selectively separate differing chemical species from oneanother, forming one or more chemical fractions. Examples of separationunits include, without limitation, distillation columns, flash drums,knock-out drums, knock-out pots, centrifuges, filtration devices, traps,scrubbers, expansion devices, membranes, solvent extraction devices, andthe like. It should be understood that separation processes described inthis disclosure may not completely separate all of one chemicalconsistent from all of another chemical constituent. It should beunderstood that the separation processes described in this disclosure“at least partially” separate different chemical components from oneanother, and that even if not explicitly stated, it should be understoodthat separation may include only partial separation. As used in thisdisclosure, one or more chemical constituents may be “separated” from aprocess stream to form a new process stream. Generally, a process streammay enter a separation unit and be divided, or separated, into two ormore process streams of desired composition. Further, in some separationprocesses, a “light fraction” and a “heavy fraction” may exit theseparation unit, where, in general, the light fraction stream has alesser boiling point than the heavy fraction stream.

As used in this disclosure, a “reactor” refers to a vessel in which oneor more chemical reactions may occur between one or more reactantsoptionally in the presence of one or more catalysts. For example, areactor may include a tank or tubular reactor configured to operate as abatch reactor, a continuous stirred-tank reactor (CSTR), or a plug flowreactor. Example reactors include packed bed reactors such as fixed bedreactors, and fluidized bed reactors. A reactor may comprise one or morecatalyst sections, such as catalyst beds, where a “section” is the areaof the reactor which houses a particular catalyst or group of multiplecatalysts. In another embodiment, separation and reactions may takeplace in a reactive separation unit.

As used in this disclosure, a “catalyst” refers to any substance whichincreases the rate of a specific chemical reaction. Catalysts describedin this disclosure may be utilized to promote various reactions, suchas, but not limited to, metathesis or cracking reactions, or both. Asused in this disclosure, a “metathesis catalyst” increases the rate of ametathesis reaction, and a “cracking catalyst” increases the rate of acracking reaction. As used in this disclosure “metathesis” generallyrefers to a chemical reaction where fragments of alkenes (olefins) areredistributed by the scission and regeneration of alkene bonds. Also, asused in this disclosure, “cracking” generally refers to a chemicalreaction where a molecule having carbon to carbon bonds is broken intomore than one molecule by the breaking of one or more of the carbon tocarbon bonds. The resulting cracked molecules may have combined the samenumber of carbon atoms as the original molecule prior to cracking.

Examples of metathesis catalysts and cracking catalysts are disclosed inco-pending Saudi Aramco U.S. Provisional Patent Application No.62/188,178 entitled “Dual Catalyst System for Propylene Production”(Attorney Docket SA 6019 MA) and co-pending Saudi Aramco U.S.Provisional Patent Application No. 62/188,129 entitled “PropyleneProduction Using a Mesoporous Silica Foam Metathesis Catalyst” (AttorneyDocket SA 6016 MA), each of which are incorporated by reference in theirentirety in this disclosure. As noted in those disclosures, suitablemetathesis catalysts may include mesoporous silica catalysts impregnatedwith metal oxide. Suitable cracking catalysts may include mordeniteframework inverted (MFI) structured silica catalysts. The mesoporoussilica catalysts may include a pore size distribution of from about 2.5nm to about 40 nm and a total pore volume of at least about 0.600 cm³/g(cubic centimeters per gram). However, it should be understood that thesystems described in this disclosure may include any suitable metathesiscatalysts and cracking catalysts, such as commercially availablecatalysts or catalysts which are the subject of future discovery.

The suitable reaction conditions for metathesis and cracking reactionsdescribed in this disclosure may vary by the catalyst compositionsemployed. However, in some embodiments, the metathesis or crackingreactions, or both, may take place at temperatures from about 500° C.(degrees Celsius) to about 600° C. in atmospheric pressure.

As described in this disclosure, “butene” may include at least 1-butene,isobutene, cis-2-butene, trans-2-butene 2-methyl-2-butene,3-methyl-1-butene, 2-methyl-1-butene, and cyclobutene. Butene issometimes referred to as butylene, and the terms “butene” and “butylene”may be used interchangeably in this disclosure. As described in thisdisclosure, “pentene” may include at least 1-pentene, cis-2-pentene,trans-2-pentene, 4-methyl-trans-2-pentene, cyclopentene, and2-methyl-2-pentene. As described in this disclosure, “hexene” mayinclude at least trans-2-hexene, trans-3-hexene, cis-3-hexene, andcyclohexene. In this disclosure, certain chemicals may be referred to inshorthand notation, where C2 stands for ethane, C3 stands for propane,C4 stands for ethane, C5 stands for pentane, C6 stands for hexane,C3=stands for propylene (or propene), C4=stands for butene (orbutylene), C5=stands for pentene, and C6=stands for hexene.

It should be understood that when two or more process stream are “mixed”or “combined” when two or more lines intersect in the schematic flowdiagrams of FIGS. 1-4. Mixing or combining may also include mixing bydirectly introducing both streams into a like reactor, separationdevice, or other system component.

Embodiments of methods to convert butene to propylene, and systems tocarry out such methods, will now be described. In one embodiment, abutene conversion system may comprise a dual catalyst reactor wheremetathesis and cracking reactions occur in a single reactor, describedsubsequently with reference to FIG. 1. Generally, according to theembodiment of FIG. 1, a stream comprising butene enters the system andundergoes a metathesis reaction, followed by a cracking reaction, in asingle reactor. In one embodiment, the reactor contains a metathesiscatalyst section upstream of a cracking catalyst section. The productstream of the cracking reaction comprises propylene and a product streamcomprising propylene may be separated from the product stream of thecracking reaction. The embodiment of FIG. 2 is similar to that of FIG.1, but comprises a recycle stream. Generally, the recycle stream of FIG.2 may comprise butane and butene and be mixed with the inlet streamcomprising butene. The stream entering the reactor of FIG. 2 may therebygenerally contain a greater percentage of butane than that of theembodiment of FIG. 1.

In other embodiments, a butene conversion system may comprise multiplereactors in series where metathesis and cracking reactions occur inseparate reactors, as described subsequently with reference to FIGS. 3and 4. The embodiment of FIG. 3 is similar to that of FIG. 1, butcomprises reactors in series in which the metathesis and crackingreactions take place. In general, the stream compositions of FIGS. 1 and3 may be similar or identical relative to like inlet streams andreaction rates. The embodiment of FIG. 4 is similar to that of FIG. 3,but comprises a recycle stream. Generally, the recycle stream of FIG. 4may comprise butane and butene and may be mixed with themetathesis-reaction product between the metathesis and crackingreactors.

It should be understood that while the embodiments of FIGS. 1-4 may havevarying mechanical apparatus or process stream compositions, or both,these embodiments generally share many of the same system components andtransfer lines. As such, processes which occur in like system componentsin the various embodiments of FIGS. 1-4 may be similar or identical withone another. For example, the system components of FIGS. 1-4 marked withthe same reference number may perform similar or identical operations inthe various embodiments. Some process streams in the embodiments ofFIGS. 1-4 may comprise similar or identical compositions, while othersmay not. For clarity, the transfer lines of the embodiments of FIGS. 1-4have each been given different reference numbers so that the compositionof their contained stream may be easily identified. However, while sometransfer lines may be in like areas and have like functions in thevarious embodiments of FIGS. 1-4, they may have substantially differentcompositions (such as in cases where recycle streams are present orwhere recycle streams reenter at differing system locations). Someprocess streams contained in like areas of FIGS. 1-4 may be similar oreven identical in like processing conditions (for example, like inletstream composition). For example, the streams of transfer lines/segmentssuch as, but not limited to: 201A, 310, 401A, and 501A may be similar orsubstantially identical in composition; 204, 304, 404, and 504 may besimilar or substantially identical in composition; 205, 305, 405, and505 may be similar or substantially identical in composition; 207, 307,407, and 507 may be similar or substantially identical in composition;203 and 403 may be similar or substantially identical in composition;206 and 406 may be similar or substantially identical in composition;208 and 408 may be similar or substantially identical in composition.The Examples, as provided in this disclosure, will help to furtherclarify the differences in process stream compositions between thevarious embodiments.

Referring now to the process-flow diagram of FIG. 1, in one embodiment,a butene conversion system 100 may include a metathesis/cracking reactor120 which comprises a metathesis catalyst section 122 and a crackingcatalyst section 124. Generally, a system inlet stream comprising buteneenters the butene conversion system 100 through a transfer line 201(including segments 201A, 201B, 201C, and 201D) and is injected into themetathesis/cracking reactor 120. The system inlet stream of segment 201Agenerally comprises at least butene, and may optionally comprise otherchemical species such as butane. For example, the system inlet streammay comprise at least about 20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, 55wt. %, 60 wt. %, 65 wt. %, or even at least about 70 wt. % butene. Thesystem inlet stream may comprise at least about 15 wt. %, 20 wt. %, 25wt. %, 30 wt. %, or even at least about 35 wt. % butane. The systeminlet stream may comprise from 0 wt. % to about 10 wt. %, 8 wt. %, 4 wt.%, 2 wt. %, or 1 wt. % ethylene, or may not substantially compriseethylene.

The system inlet stream may be processed by one or more systemcomponents prior to entering the metathesis/cracking reactor 120. Insuch embodiments, the transfer line 201 may comprise several segments(depicted as 201A, 201B, 201C, and 201D) which may be separated bysystem components such as an impurities removal device 110, heattransfer device 112, and heat transfer device 114. The impuritiesremoval device 110 may remove oxygenates present in the system inletstream. In one embodiment, the impurities removal device 110 comprises acatalytic bed. Heat transfer device 112 may be a heat exchanger thatserves to elevate the temperature of the system inlet stream byexchanging energy with the stream present in transfer line 203A. Heattransfer device 114 may be a heater that serves to further heat thesystem inlet stream. It should be understood that the impurities removaldevice 110, heat transfer device 112, and heat transfer device 114 areoptional components in the butene conversion system 100. It should beunderstood that all streams located in the various segments of transferline 201 (that is, 201A, 201B, 201C, and 201D) are considered portionsof the system inlet stream, even though the chemical composition,temperature, or other properties of the system inlet stream may bedifferent in the various segments 201A, 201B, 201C, 201D.

Still referring to FIG. 1, the metathesis/cracking reactor 120 comprisesa metathesis catalyst section 122 and a cracking catalyst section 124.The metathesis catalyst section 122 is positioned generally upstream ofthe cracking catalyst section 124, that is, the cracking catalystsection 124 is positioned generally downstream of the metathesiscatalyst section 122. The system inlet stream from segment 201D entersthe metathesis/cracking reactor 120 and contacts the metathesis catalystto undergo a metathesis reaction in the metathesis catalyst section 122to form a metathesis-reaction product. Following the metathesisreaction, the metathesis-reaction product is contacted with the crackingcatalyst to undergo cracking a cracking reaction in the crackingcatalyst section 124. The cracking reaction forms a cracking-reactionproduct. Generally, the reactants that undergo cracking or metathesis,or both, intimately intermingle with the respective catalysts duringreaction.

As used in this disclosure, a “metathesis-reaction product” refers tothe entire product mixture resulting from the metathesis reaction,including any portion of the product mixture which does not undergometathesis. Additionally, as used in this disclosure “cracking-reactionproduct” refers to the entire product mixture resulting from thecracking reaction, including any portion of the product mixture whichdoes not undergo cracking. For example, the cracking-reaction productinclude all components of the process stream leaving the reactor wherecracking took place.

The cracking-reaction product is passed out of the metathesis/crackingreactor 120 in a cracking-reaction product stream via transfer line 203.The cracking-reaction product may comprise, consist, or consistessentially of a mixture of alkanes and alkenes, including, but notlimited to, ethylene, propylene, butene, pentene, hexene, heptene,ethane, propane, butane, pentane, hexane, and heptane. Thecracking-reaction product may comprise at least about 2 wt. %, 4 wt. %,6 wt. %, 8 wt. %, 10 wt. %, 12 wt. %, 14 wt. %, 16 wt. %, 18 wt. %, 20wt. %, 22 wt. %, 24 wt. %, 26 wt. %, 28 wt. %, or even at least about 30wt. % propylene.

The cracking-reaction product stream of transfer line 203A formed in themetathesis/cracking reactor 120 may be separated into one or morestreams having desired compositions. Generally, a product streamcomprising propylene, such as shown in transfer line 207 in FIG. 1, maybe formed by separating the cracking-reaction product stream. Theproduct stream may comprise at least about 50 wt. %, 60 wt. %, 70 wt. %,80 wt. %, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. %, or even atleast about 99 wt. % propylene. It should be understood that a widevariety of separation processes may be utilized to produce the productstream comprising propylene.

In one embodiment, as shown in FIG. 1 the cracking-reaction product maybe passed to one or more separation units via transfer line 203 whichmay be comprised of segment 203A and segment 203B, where the segmentsare divided by heat transfer device 112. The cracking-reaction productmay enter separation unit 130 where light constituents, such as ethyleneand ethane may be removed. Light constituents such as ethylene may bepurged from the butene conversion system 100 via transfer line 204 ormay be utilized in other chemical systems via transfer line 205. Thestreams contained in transfer line 204 and transfer line 205 maycomprise, consists, or consist essentially of ethylene. For example, thestream of transfer line 204 or transfer line 205, or both, may compriseat least about 50 wt. %, 60 wt. %, 70 wt. %, 80 wt. %, 90 wt. %, 95 wt.%, 96 wt. %, 97 wt. %, 98 wt. %, or even at least about 99 wt. %ethylene. The heavy fraction from separation unit 130 may be passed outof separation unit 130 via transfer line 206. The process stream oftransfer line 206 may comprise a mixture of alkanes and alkenes,including, but not limited to, one or more of propylene, butene,pentene, hexene, heptene, ethane, propane, butane, pentane, hexane, andheptane. The process stream of transfer line 206 may enter separationunit 140 where propylene is separated from other constituents. The lightfraction (that is, propylene) may exit the separation unit 140 viatransfer line 207 as a propylene product stream. The propylene productstream contained in transfer line 207 may comprise, consists, or consistessentially of propylene. For example, the stream of transfer line 204or transfer line 205, or both, may comprise at least about 50 wt. %, 60wt. %, 70 wt. %, 80 wt. %, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98wt. %, or even at least about 99 wt. % propylene. The heavy fractionfrom separation unit 140 may be passed out of separation unit 140 viatransfer line 208. The process stream of line 208 may comprise a mixtureof alkanes and alkenes, including, but not limited to, one or more ofbutene, pentene, hexene, heptene, propane, butane, pentane, hexane, andheptane. The stream of transfer line 208 may be purged from the buteneconversion system 100 as an end product or may be further separated indownstream processing.

As referred to previously, the embodiment of FIG. 2 is similar to thatof FIG. 1, but comprises a recycle stream majorly comprising butane andbutene. Generally, in the embodiment of FIG. 2, the recycle stream oftransfer line 312 may comprise butane and butene and be mixed with theinlet stream of transfer line 310 which comprises butene. The stream oftransfer line segment 301D enters the reactor and may thereby generallycontain a greater percentage of butane than the stream of transfer linesegment 201D of FIG. 1. Generally, the addition of the recycle stream asdescribed with reference to FIG. 2 may increase propylene selectivityand propylene yield.

Referring now to the process-flow diagram of FIG. 2, in one embodiment,a butene conversion system 200 may include a metathesis/cracking reactor120 which comprises a metathesis catalyst section 122 and a crackingcatalyst section 124. Generally, a system inlet stream comprising buteneenters the butene conversion system 200 through transfer line 310. Thesystem inlet stream of transfer line 310 may generally comprises atleast butene, and may optionally comprise other chemical species such asbutane. For example, the system inlet stream of transfer line 310 maycomprise at least about 20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, 55 wt.%, 60 wt. %, 65 wt. %, or even at least about 70 wt. % butene, and maycomprise at least about 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, or atleast about 35 wt. % butane. The system inlet stream of transfer line310 may comprise from 0 wt. % to about 10 wt. %, 8 wt. %, 4 wt. %, or 2wt. % ethylene, or may not substantially comprise ethylene.

The system inlet stream in transfer line 310 is combined with a recyclestream in transfer line 312 to form a mixed stream present in transferline 301. The mixed stream is passed through transfer line 301 and isintroduced into the metathesis/cracking reactor 120. In embodiments, therecycle stream of transfer line 312 may comprise butene and butane. Forexample, the recycle stream of transfer line 312 may comprise at leastabout 5 wt. %, 10 wt. %, 15 wt. %, or even at least about 20 wt. %butene, and may comprise at least about 50 wt. %, 60 wt. %, 70 wt. %, oreven greater than about 80 wt. % butane. The recycle stream of transferline 312 may comprise at least about 80 wt. %, 90 wt. % or even at leastabout 95 wt. % of the combination of butane and butene.

The mixed stream of transfer line 301 may comprise butane and butene.For example, the mixed stream of transfer line 301 may comprise at leastabout 5 wt. %, 10 wt. %, 15 wt. %, 20 wt %, 25 wt. %, 30 wt. %, or evenat least about 35 wt. % butene, and may comprise at least about 40 wt.%, 50 wt. %, 60 wt. %, 70 wt. %, or even at least about 80 wt. % butane.The mixed stream of transfer line 301 may comprise at least about 80 wt.%, 90 wt. % or even at least about 95 wt. % of the combination of butaneand butene.

The mixed stream may be processed by one or more system components priorto entering the metathesis/cracking reactor 120. In such embodiments,the transfer line 301 may comprise several segments (depicted as 301A,301B, 301C, and 301D) which may be separated by system components suchas an impurities removal device 110, heat transfer device 112, and heattransfer device 114.

Following the metathesis and cracking reactions in reactor 120, thecracking-reaction product of transfer line segment 303A may comprise,consist, or consist essentially of a mixture of alkanes and alkenes,including, but not limited to, one or more of ethylene, propylene,butene, pentene, hexene, heptene, ethane, propane, butane, pentane,hexane, and heptane. For example, the cracking-reaction product of theembodiment of FIG. 2 may comprise at least about 2 wt. %, 4 wt. %, 6 wt.%, 8 wt. %, 10 wt. %, 12 wt. %, 14 wt. %, 16 wt. %, 18 wt. %, or even atleast about 20 wt. % propylene.

As is described with reference to the embodiment of FIG. 1, thecracking-reaction product of the embodiment of FIG. 2, formed in themetathesis/cracking reactor 120, may be separated into one or morestreams having desired compositions. Generally, a product streamcomprising propylene (of transfer line 307) may be formed by separatingpropylene from the cracking-reaction product stream of transfer line303A. The product stream of transfer line 307 may comprise at leastabout 50 wt. %, 60 wt. %, 70 wt. %, 80 wt. %, 90 wt. %, 95 wt. %, 96 wt.%, 97 wt. %, 98 wt. %, or even at least about 99 wt. % propylene. Itshould be understood that a wide variety of separation processes may beutilized to produce the product stream comprising propylene.

In one embodiment, as shown in FIG. 2, the cracking-reaction product maybe introduced into one or more separation units via transfer line 303which may be comprised of segment 303A and segment 303B, where thesegments are divided by heat transfer device 112. Similar to theembodiment of FIG. 1 described previously, the cracking-reaction productmay enter separation unit 130 where ethylene and other lightconstituents may be at least partially removed. Following the ethyleneseparation by separation device 130, propylene may be separated from theheavy fraction of separation unit 130 in separation unit 140. The heavyfraction from separation unit 140 may be passed out of separation unit140 via transfer line 308. The stream of line 308 may comprise a mixtureof alkanes and alkenes, including, but not limited to, one or more ofbutene, pentene, hexene, heptene, propane, butane, pentane, hexane, andheptane.

The process stream of transfer line 308 may be injected into separationunit 150 where one or more fractions may be separated from one another.In one embodiment, a heavy fraction may exit separation unit 150 in astream contained in transfer line 314. The stream of transfer line 314may comprise one or more of pentene, pentane, hexene, heptene, pentane,hexane, and heptane. The light fraction of separation unit 150, whichcomprises primarily butene and butane, may exit separation unit 150 inthe recycle stream contained in transfer line 312. A portion of therecycle stream contained in transfer line 312 may be purged from thesystem 200 via transfer line 316. The remaining portion may be recycledinto the system 200 by combining the stream of transfer line 312 withthe system inlet stream of transfer line 310.

In another embodiment, as described with reference to FIG. 3, a buteneconversion system 300 may comprise multiple reactors in series wheremetathesis and cracking reactions occur in separate reactors. Theembodiment of FIG. 3 is similar to that of FIG. 1, but comprisesseparate metathesis and catalyst reactors in series. In someembodiments, it may be advantageous to utilize reactors in series, suchas when the metathesis reaction and cracking reaction are performed atdifferent reaction conditions (such as different temperature or/orpressure). The other system components (non-reactor) of FIG. 3 maygenerally be similar or identical to those described with reference toFIG. 1. The embodiment of FIG. 3 may result in similar or identicalbutene conversion, propylene selectivity, and propylene yield as comparewith the embodiment of FIG. 1. Additionally, the compositions of theprocess streams of the embodiment of FIG. 3 may be similar or identicalto those of FIG. 1.

Referring now to the process-flow diagram of FIG. 3, in one embodiment,a butene conversion system 300 may include a metathesis reactor 121,which comprises a metathesis catalyst section 122, and a crackingreactor 123, which comprises a cracking catalyst section 124. Generally,a system inlet stream comprising butene enters the butene conversionsystem 300 through a transfer line 401 and is injected into themetathesis reactor 121. The system inlet stream generally comprises atleast butene, and may optionally comprise other chemical species such asbutane. For example, the system inlet stream of transfer line 401 maycomprise at least about 20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, 55 wt.%, 60 wt. %, 65 wt. %, or even at least about 70 wt. % butene. Thesystem inlet stream may comprise at least about 15 wt. %, 20 wt. %, 25wt. %, 30 wt. %, or even at least about 35 wt. % butane.

Still referring to FIG. 3, the metathesis reactor 121 comprises ametathesis catalyst section 122, such as a metathesis catalyst bed, andthe cracking reactor 123 comprises a cracking catalyst section 124, suchas a cracking catalyst bed. The metathesis reactor 121 and the crackingreactor 123 are arranged in series where the metathesis reactor 121 ispositioned generally upstream of the cracking reactor 123, that is, thecracking reactor 123 is positioned generally downstream of themetathesis reactor 121. The system inlet stream from segment 401D entersthe metathesis reactor 121 and undergoes a metathesis reaction in themetathesis catalyst section 122 to form a metathesis-reaction product.The metathesis-reaction product may be passed out of the metathesisreactor in a metathesis-reaction product stream via transfer line 410.The metathesis-reaction product stream enters the cracking reactor 123and is cracked in a cracking reaction in the cracking catalyst section124. The cracking reaction forms a cracking-reaction product. Thecracking-reaction product is passed out of the cracking reactor 123 in acracking-reaction product stream via transfer line 403. Thecracking-reaction product may comprise, consist, or consist essentiallyof a mixture of alkanes and alkenes, including, but not limited to, oneor more of ethylene, propylene, butene, pentene, hexene, heptene,ethane, propane, butane, pentane, hexane, and heptane. Thecracking-reaction product may comprise at least about 2 wt. %, 4 wt. %,6 wt. %, 8 wt. %, 10 wt. %, 12 wt. %, 14 wt. %, 16 wt. %, 18 wt. %, 20wt. %, 22 wt. %, 24 wt. %, 26 wt. %, 28 wt. %, or even at least about 30wt. % propylene.

Similar to the embodiment of FIG. 1, in the embodiment of FIG. 3 thecracking-reaction product may be separated into one or more streamshaving desired compositions. Generally, a product stream comprisingpropylene (in transfer line 407) may be formed by separating propylenefrom the other components of the cracking-reaction product stream. Theproduct stream of transfer line 407 may comprise at least about 50 wt.%, 60 wt. %, 70 wt. %, 80 wt. %, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %,98 wt. %, or even at least about 99 wt. % propylene. It should beunderstood that a wide variety of separation processes may be utilizedto produce the product stream comprising propylene. As shown in FIG. 3,multiple separation units may be utilized.

Now with reference to FIG. 4, the embodiment of FIG. 4 is similar tothat of FIG. 3, but comprises a recycle stream in transfer line 512.Generally, the recycle stream of FIG. 3 (in transfer line 512) maycomprise butane and butene and may be mixed with the metathesis-reactionproduct stream in transfer line 510, located between the metathesisreactor 121 and cracking reactor 123.

Still referring to the process-flow diagram of FIG. 4, in oneembodiment, a butene conversion system 400 may include a metathesisreactor 121 which comprises a metathesis catalyst section 122 and acracking reactor 123 which comprises a cracking catalyst section 124.Generally, a system inlet stream comprising butene enters the buteneconversion system 400 through a transfer line 501 and is injected intothe metathesis reactor 121. The system inlet stream generally comprisesat least butene, and may optionally comprise other chemical species suchas butane. For example, the system inlet stream may comprise at leastabout 20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt.%, or even 70 wt. % butene. The system inlet stream may comprise atleast about 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, or even 35 wt. %butane.

The system inlet stream from segment 501D may enter the metathesisreactor 121 and undergoes a metathesis reaction in the metathesiscatalyst section 122 to form a metathesis-reaction product. Themetathesis-reaction product may be passed out of the metathesis reactor121 in a metathesis-reaction product stream via transfer line 510. Themetathesis-reaction product stream contained in transfer line 510 iscombined with the recycle stream of transfer line 512 to form a mixedstream in transfer line 520. In embodiments, the recycle stream oftransfer line 512 may comprise butene and butane. For example, therecycle stream of transfer line 512 may comprise at least about 5 wt. %,10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, or even at least about35 wt. % butene, and may comprise at least about 40 wt. %, 50 wt. %, 60wt. %, 70 wt. %, or even at least about 80 wt. % butane. The recyclestream of transfer line 512 may comprise at least about 80 wt. %, 90 wt.%, or even at least about 95 wt. % of the combination of butane andbutene.

The mixed stream of transfer line 520 enters the cracking reactor 123and is cracked in a cracking reaction in the cracking catalyst section124. The cracking reaction forms a cracking-reaction product. Thecracking-reaction product is passed out of the cracking reactor 123 in acracking-reaction product stream via transfer line 503. Thecracking-reaction product may comprise, consist, or consist essentiallyof a mixture of alkanes and alkenes, including, but not limited to, oneor more of ethylene, propylene, butene, pentene, hexene, heptene,ethane, propane, butane, pentane, hexane, and heptane. Thecracking-reaction product may comprise at least about 1 wt. %, 2 wt. %,3 wt. %, 4 wt. %, 5 wt. %, 6 wt. %, 7 wt. %, 8 wt. %, 10 wt. %, 15 wt.%, or even at least about 20 wt. % propylene.

As described with reference to the embodiments of FIG. 3, thecracking-reaction product (in transfer line 503A) formed in the crackingreactor 123 may be separated into one or more streams having desiredcompositions. Generally, a product stream comprising propylene (intransfer line 507) may be formed by separating propylene from the othercomponents of the cracking-reaction product stream. The product streamof transfer line 507 may comprise at least about 50 wt. %, 60 wt. %, 70wt. %, 80 wt. %, 90 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. %, oreven at least about 99 wt. % propylene. It should be understood that awide variety of separation processes may be utilized to produce theproduct stream comprising propylene.

In one embodiment, as shown in FIG. 4 the cracking-reaction product maybe introduced to one or more separation units via transfer line 503which may be comprised of segment 503A and segment 503B, where thesegments are divided by heat transfer device 112. Similar to theembodiment of FIGS. 1 and 3, the cracking-reaction product may enterseparation unit 130 where ethylene and other light constituents may beremoved. Following the ethylene separation by separation unit 130,propylene may be separated from the heavy fraction of separation unit130 in separation unit 140. The heavy fraction from separation unit 140may be passed out of separation unit 140 via transfer line 508. Thestream of line 508 may comprise a mixture of alkanes and alkenes,including, but not limited to, one or more of butene, pentene, hexene,heptene, propane, butane, pentane, hexane, and heptane.

The process stream of transfer line 508 may be injected into separationunit 150 where one or more fractions may be separated from one another.In one embodiment, a bottoms fraction may exit separation unit 150 in astream contained in transfer line 514. The process stream of transferline 514 may comprise one or more of pentene, pentane, hexene, hexaneheptene, and heptane. The light fraction may exit separation unit 150 ina stream contained in transfer line 516 and be purged from the system400. The stream of transfer line 516 may comprise one or more of buteneand butane, for example, at least about 20 wt. %, 30 wt. %, 40 wt. %, oreven at least about 50 wt. % butane. A recycle stream contained intransfer line 512 may be recycled into the system 400 by combining thestream of transfer line 512 with the metathesis product stream oftransfer line 510. In one embodiment, the recycle stream of 512 may be aportion of the top fraction stream of transfer line 516.

Generally, a stream containing butane and butene, suitable as the inletstream in the embodiments described in this disclosure, may be producedfrom refining operations. This stream containing butane and butene maybe separated into fractions to form a first raffinate, second raffinate,and third raffinate. In one embodiment, the system inlet stream may be araffinate stream from an olefin refining system, such as a conventionalrefinery. The stream produced from the refining operation may generallycomprise a C4 alkanes and alkenes, including butanes, butenes, andbutadienes. A “first raffinate” may be produced by separating1,3-butadiene from the other C4 constituents in the stream. The firstraffinate may comprise isobutylene, cis-2-butene, and trans-2-butene.For example, the first raffinate may comprise, or consist essentiallyof, from about 40 wt. % to about 50 wt. %, from about 35 wt. % to about55 wt. %, or from about 30 wt. % to about 60 wt. % of isobutene and fromabout 30 wt. % to about 35 wt. %, from about 25 wt. % to about 40 wt. %,or from about 20 wt. % to about 45 wt. % of the sum of cis-2-butene andtrans-2-butene. A “second raffinate” may be produced by separatingisobutylene from the other C4 constituents of the first raffinate. Forexample, the second raffinate may comprise, or consist essentially of,from about 50 wt. % to about 60 wt. %, from about 45 wt. % to about 65wt. %, or from about 40 wt. % to about 70 wt. % of the sum ofcis-2-butene and trans-2-butene, from about 10 wt. % to about 15 wt. %,from about 5 wt. % to about 20 wt. %, or from about 0 wt. % to about 25wt. % of 1-butene, and from about 15 wt. % to about 25 wt. %, from about10 wt. % to about 30 wt. %, or from about 5 wt. % to about 35 wt. % ofbutane. The inlet stream of the systems described herein may besubstantially free of isobutene, and may consist essentially of2-butenes and n-butanes.

Referring to embodiments of the catalyzed reactions described herein, asshown in the following Formulas 1 and 2, “metathesis” or“self-metathesis” may generally be a two-step process: 2-buteneisomerization and then cross-metathesis using the metathesis catalystsystem. As shown in the following Formula 3, in embodiments “catalyzedcracking” may refer to the conversion of C₄-C₆ alkenes to propylene andother alkanes and/or alkenes, for example, C₁-C₂ alkenes.

Referring to Formulas 1-3, the “metathesis” and “catalytic cracking”reactions are not limited to these reactants and products; however,Formulas 1-3 provide a basic illustration of the reaction methodologyaccording to some embodiments. As shown in Formulas 1 and 2, metathesisreactions take place between two alkenes. The groups bonded to thecarbon atoms of the double bond are exchanged between the molecules toproduce two new alkenes with the swapped groups. The specific catalystthat is selected for the olefin metathesis reaction may generallydetermine whether a cis-isomer or trans-isomer is formed, as thecoordination of the olefin molecules with the catalyst play an importantrole, as do the steric influences of the substituents on the double bondof the newly formed molecule.

In one embodiment, the present dual catalyst system comprises: amesoporous silica catalyst, which is a mesoporous silica catalystsupport impregnated with metal oxide; and a mordenite framework inverted(MFI) structured silica catalyst downstream of the mesoporous silicacatalyst. Various structures are contemplated for the mesoporous silicacatalyst support, for example, a molecular sieve. As used in theapplication, “mesoporous” means that the silica support has a narrowpore size distribution. Specifically, the mesoporous silica catalystincludes a narrow pore size distribution of from about 2.5 nm(nanometers) to about 40 nm and a total pore volume of at least about0.600 cm³/g. Without being bound by theory, the present pore sizedistribution and pore volume are sized to achieve better catalyticactivity and reduced blocking of pores by metal oxides, whereas smallerpore volume and pore size catalyst systems are susceptible to poreblocking and thereby reduced catalytic activity.

Moreover, utilizing an MFI structured silica catalyst downstream of themesoporous silica catalyst surprisingly provides the best yield ofpropylene from a butene stream. The person of ordinary skill in the artwould have expected the best yield by first cracking butene to propyleneand then cracking any remaining butene via metathesis. However, it wassurprisingly found that propylene yield is increased, and additionallythe combined yield of propylene and ethylene is increased by placing theMFI structured silica catalyst downstream of the mesoporous silicacatalyst.

In one or more embodiments, the pore size distribution of the mesoporoussilica catalyst may range from about 2.5 nm to about 40 nm, or about 2.5nm to about 20 nm, or about 2.5 nm to about 4.5 nm, or about 2.5 nm toabout 3.5 nm, or about 8 nm to about 18 nm, or about 12 nm to about 18nm. In further embodiments, the total pore volume may be from about0.600 cm³/g to about 2.5 cm³/g, or about 0.600 cm³/g to about 1.5 cm³/g,or about 0.600 cm³/g to about 1.3 cm³/g, or about 0.600 cm³/g to about0.800 cm³/g, or about 0.600 cm³/g to about 0.700 cm³/g, or about 0.900cm³/g to about 1.3 cm³/g.

Moreover, while broader ranges are contemplated, the mesoporous silicacatalyst may, in one or more embodiments, include a surface area ofabout 250 square meters/gram (m²/g) to about 600 m²/g. In furtherembodiments, the mesoporous silica catalyst may have a surface area offrom about 450 m²/g to about 600 m²/g, or about 250 m²/g to about 350m²/g, or about 275 m²/g to about 325 m²/g, or about 275 m²/g to about300 m²/g. Further, the mesoporous silica catalyst may have a totalacidity of up to about 0.5 millimole/gram (mmol/g), or about 0.01 mmol/gto about 0.5 mmol/g, or about 0.1 mmol/g to about 0.5 mmol/g, or about0.3 mmol/g to about 0.5 mmol/g, or about 0.4 mmol/g to about 0.5 mmol/g.Acidity is generally maintained at or less than about 0.5 mmol/g toyield the desired selectivity of propylene and reduced production ofundesirable byproducts such as aromatics. Increasing acidity mayincrease the overall butene conversion; however, this increasedconversion may lead to less selectivity and increased production ofaromatic byproducts, which can lead to catalyst coking and deactivation.

Furthermore, the mesoporous silica catalyst may have a particle size offrom about 20 nm to about 200 nm, or about 50 nm to about 150 nm, orabout 75 nm to about 125 nm. In additional embodiments, the mesoporoussilica catalyst may have an individual crystal size of about 1 μm toabout 100 μm, or about 10 μm to about 40 μm.

Various formulations for the mesoporous silica support, as well asmethods of making the formulation, are contemplated. For example, themesoporous silica catalyst support may be produced via wet impregnation,hydrothermal synthesis, or both. Additionally, the mesoporous silicacatalyst support may be characterized by an ordered pore structure. Forexample, this ordered structure may have a hexagonal array of pores. Onesuitable embodiment of a mesoporous silica support with a hexagonal porearray may be the Santa Barbara Amorphous (SBA-15) mesoporous silicamolecular sieve. Alternatively, another suitable embodiment of amesoporous silica support is the CARiACT Q-10 (Q-10) spherical catalystsupport produced by Fuji Silysia Chemical Ltd.

The catalyst of the metathesis reaction is the impregnated metal oxideof the silica support. The metal oxide may comprise one or oxides of ametal from the Groups 6-10 of the IUPAC Periodic Table. In one or moreembodiments, the metal oxide may be an oxide of molybdenum, rhenium,tungsten, or combinations thereof. In a specific embodiment, the metaloxide is tungsten oxide (WO₃). It is contemplated that various amountsof metal oxide may be impregnated into the mesoporous silica catalystsupport. For example and not by way of limitation, the molar ratio ofsilica to metal oxide, for example, WO₃, is about 5 to about 60, orabout 5 to about 15, or about 20 to about 50, or about 20 to about 40,or about 25 to about 35.

In one or more embodiments, the metathesis catalyst may compriseamorphous mesoporous silica foam impregnated with metal oxides. As usedin the application, “amorphous mesoporous silica foam” means a silicasupport with a non-ordered structure and a narrow pore sizedistribution. This non-ordered structure may be random and thusdifferent than the disclosed hexagonal or cubic structures ofconventional silica supports. Specifically, the amorphous mesoporoussilica foam has a narrow pore size distribution of at least 3 nm toabout 40 nm and a total pore volume of at least 0.700 cm³/g. Withoutbeing bound by theory, the present pore size distribution and porevolume are sized to achieve better catalytic activity and reducedblocking of pores by metal oxides, whereas smaller pore volume and poresize metathesis catalysts are susceptible to pore blocking and therebyreduced catalytic activity. Reduced blocking leads to higher dispersionof metal oxide species, such as WO₃, on the amorphous mesoporous silicafoam. Higher WO₃ dispersion leads to higher metathesis activity and thushigher propylene yield.

In one or more embodiments, the pore size distribution of the amorphousmesoporous silica foam impregnated with metal oxides may range from atleast 3 nm to about 40 nm, or from about 3 nm to about 20 nm, or fromabout 4 nm to about 10 nm, or from about 4 nm to about 8 nm, or fromabout 4 nm to about 6 nm. In further embodiments, the total pore volumemay be from at least 0.700 cm³/g to about 2.5 cm³/g, or from about 0.800cm³/g to about 2.5 cm³/g, or from about 0.800 cm³/g to about 1.5 cm³/g,or from about 0.800 cm³/g to about 1.25 cm³/g, or from about 0.800 cm³/gto about 1.0 cm³/g, or from about 0.850 cm³/g to about 1.0 cm³/g.

Moreover, the amorphous mesoporous silica foam impregnated with metaloxides may have a total acidity from about 0.125 millimole/gram (mmol/g)to about 0.500 mmol/g. Without being bound by theory, if the materialexceeds 0.500 mmol/g, other detrimental side reactions may result, suchas cracking and hydrogen transfer reactions. In further embodiments, theamorphous mesoporous silica foam impregnated with metal oxides may havea total acidity from about 0.125 mmol/g to about 0.250 mmol/g, or fromabout 0.125 mmol/g to about 0.150 mmol/g. While various surface areasare contemplated, the metathesis catalyst may, in one or moreembodiments, have a surface area of at least about 400 meters²/g (m²/g),or from about 400 m²/g about 800 m²/g, or from about 400 m²/g to about500 m²/g, or from about 400 m²/g to about 450 m²/g, or from about 425m²/g to about 450 m²/g.

The catalyst of the metathesis reaction may be the impregnated metaloxide of the silica foam. The metal oxide may comprise one or oxides ofa metal from the Periodic Table IUPAC Group Numbers 6-10. In one or moreembodiments, the metal oxide may be an oxide of molybdenum, rhenium,tungsten, or combinations thereof. In a specific embodiment, the metaloxide is tungsten oxide (WO₃). It is contemplated that various amountsof metal oxide may be impregnated into the amorphous mesoporous silicafoam. For example and not by way of limitation, the molar ratio ofsilica to metal oxide, for example, WO₃, is about 1 to about 50, orabout 1 to about 40, or about 5 to about 30, or about 5 to about 15.Moreover, the metathesis catalyst may include from about 1 to about 50%by weight, or from about 2 to about 25% by weight, or from about 5 toabout 15% by weight metal oxide, for example, WO₃.

Additionally, other optional components may be included into theimpregnated mesoporous silica foam catalyst. For example, the metathesiscatalyst may include a structuring agent. In one embodiment, thestructuring agent is a tri-block copolymer structuring agent. In afurther embodiment, the tri-block copolymer structuring agent is apoly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethyleneglycol) structure, which may be also called a poloxamer structure. Onesuitable commercial embodiment of the surfactant tri-block copolymerstructuring agent is Pluronic® P123 by BASF Corporation.

Additionally, various silica structures are contemplated for the MFIstructured silica catalyst. For example, the MFI structured silicacatalyst may include MFI structured aluminosilicate zeolite catalysts orMFI structured silica catalysts free of alumina. As used herein, “free”means less than 0.001% by weight of alumina in the MFI structured silicacatalyst. Moreover, it is contemplated that the MFI structured silicacatalyst may include other impregnated metal oxides in addition to or asan alternative to alumina. Like the mesoporous silica catalyst, the MFIstructured catalysts may have alumina, metal oxides, or both impregnatedin the silica support. In addition to or as a substitute for alumina, itis contemplated to include the metal oxides listed prior, specifically,one or more oxides of a metal from Groups 6-10 of the IUPAC PeriodicTable, more specifically, metal oxides of molybdenum, rhenium, tungsten,titanium, or combinations thereof.

For the MFI structured aluminosilicate zeolite catalysts, variousamounts of alumina are contemplated. In one or more embodiments, the MFIstructured aluminosilicate zeolite catalysts may have a molar ratio ofsilica to alumina of about 5 to about 5000, or about 100 to about 4000,or about 200 to about 3000, or about 1500 to about 2500, or about 1000to about 2000. Various suitable commercial embodiments of the MFIstructured aluminosilicate zeolite catalysts are contemplated, forexample, ZSM-5 zeolites such as MFI-280 produced by ZeolystInternational or MFI-2000 produced by Saudi Aramco.

Various suitable commercial embodiments are also contemplated for thealumina free MFI structured catalysts. One such example is Silicalite-1produced by Saudi Aramco.

The MFI structured silica catalyst may include a pore size distributionof from about 1.5 nm to 3 nm, or about 1.5 nm to 2.5 nm. Furthermore,the MFI structured silica catalyst may have a surface area of from about300 m²/g to about 425 m²/g, or about 340 m²/g to about 410 m²/g.Additionally, the MFI structured silica catalyst may have a totalacidity of from about 0.001 mmol/g to about 0.1 mmol/g, or about 0.01mmol/g to about 0.08 mmol/g. The acidity is maintained at or less thanabout 0.1 mmol/g in order to reduce production of undesirable byproductssuch as aromatics. Increasing acidity may increase the amount ofcracking; however, this increased cracking may also lead to lessselectivity and increased production of aromatic byproducts, which canlead to catalyst coking and deactivation.

In some cases, MFI structured silica catalyst may be modified with anacidity modifier to adjust the level of acidity in the MFI structuredsilica catalyst. For example, these acidity modifiers may include rareearth modifiers, phosphorus modifiers, potassium modifiers, orcombinations thereof. However, as the present embodiments are focused onreducing the acidity to a level at or below 0.1 mmol/g, the presentstructured silica catalyst may be free of acidity modifier, such asthose selected from rare earth modifiers, phosphorus modifiers,potassium modifiers, or combinations thereof. As used herein, “free ofacidity modifiers” means less than less than 0.001% by weight of aciditymodifier in the MFI structured silica catalyst.

Further, the MFI structured silica catalyst may have a pore volume offrom about 0.1 cm³/g to about 0.3 cm³/g, or about 0.15 cm³/g to about0.25 cm³/g. Additionally, the MFI structured silica catalyst may have anindividual crystal size ranging from about 10 nm to about 40 μm, or fromabout 15 μm to about 40 μm, or from about 20 μm to about 30 μm. Inanother embodiment, the MFI structured silica catalyst may have anindividual crystal size in a range of from about 1 μm to about 5 μm.

Moreover, various amounts of each catalyst are contemplated for thepresent dual catalyst system. For example, it is contemplated that theratio by volume of metathesis catalyst to cracking catalyst may rangefrom about 5:1 to about 1:5, or about 2:1 to about 1:2, or about 1:1.

In operation, a product stream comprising propylene is produced from abutene containing stream via metathesis conversion by contacting thebutene stream with the dual catalyst system. The butene stream maycomprise 2-butene, and optionally comprises one or more isomers, such as1-butene, trans-2-butene, and cis-2-butene. The present discussioncenters on butene based feed streams; however, it is known that otherC₁-C₆ components may also be present in the feed stream.

The mesoporous silica catalyst may be a metathesis catalyst whichfacilitates isomerization of 2-butene to 1-butene followed bycross-metathesis of the 2-butene and 1-butene into a metathesis productstream comprising propylene, and other alkenes/alkanes such as pentene.The MFI structured silica catalyst, which is downstream of themetathesis catalyst, is a cracking catalyst which produces propylenefrom C₄ or C₅ olefins in the metathesis product stream, and may alsoyield ethylene.

While the specific catalyst compositions have been described, it shouldbe understood that embodiments of the methods and systems of the presentapplication may incorporate any catalyst that can be utilized tometathesize or crack the reactant compositions described.

EXAMPLES

The various embodiments of methods and systems for the cracking of alight fuel fraction and a heavy fuel fraction by fluidized catalyticcracking will be further clarified by the following examples. Theexamples are illustrative in nature, and should not be understood tolimit the subject matter of the present disclosure.

Example 1

The systems of FIG. 1 were computer modeled using Aspen Plus®(commercially available from AspenTech). The subsequent tables (Tables1-4) depict the stream compositions as well as thermal properties forselected streams. The reaction rates supplied for the simulation wererepresentative of experimental reaction rates for the metathesiscatalyst W-SBA-15 and the cracking catalyst MFI-2000, as described inExamples 1, 3, and 6 of co-pending Saudi Aramco U.S. Provisional PatentApplication No. 62/188,178 entitled “Dual Catalyst System for PropyleneProduction” (Attorney Docket SA 6019 MA). A system inlet stream of 35wt. % cis-2-butene, 35 wt. % trans-2-butene, and 30 wt. % n-butane wasused for the model. The stream numbers of the tables corresponds withthe stream or stream segment shown in FIG. 1. Simulations were run for100% efficiency and 80% efficiency. Data for the simulations is providedon a weight basis and a mole basis for each simulation. Specifically,Table 1 depicts data for a simulation of the system of FIG. 1 with 100%efficiency and shows components on a mass basis. Table 2 depicts datafor a simulation of the system of FIG. 1 with 100% efficiency and showscomponents on a mole basis. Table 3 depicts data for a simulation of thesystem of FIG. 1 with 80% efficiency and shows components on a massbasis. Table 4 depicts data for a simulation of the system of FIG. 1with 80% efficiency and shows components on a mole basis. Additionally,FIG. 6 depicts a bar graph displaying the product distribution of thesystem of FIG. 1 as shown in Table 1 where, on the bar graph,“Propylene” corresponds with the stream of transfer line 207, “Ethylene”corresponds with the stream of transfer line 205, “Light Purge”corresponds with the stream of transfer line 204, and “C4/C5+Heavy”corresponds with the stream of transfer line 208. FIG. 7 depicts a bargraph displaying the butene conversion products following the metathesisand cracking reactions. The product distribution of FIG. 6 and thebutene conversion products of FIG. 7 are based on the Aspen simulationsof Table 1.

TABLE 1 FIG. 1 with 100% Efficiency in wt. % Stream Number 201A 201D203A 203B 204 205 206 207 208 Mole Flow, kmol/hr 100 100 120.2 120.219.7 2.2 98.3 41.3 57 Mass Flow, kg/hr 5670 5670 5670 5670 555 62 50531738 3315 Volume Flow m³/hr 6750 6750 8119 9.4 1.3 0.1 10.8 3.6 7.1Enthalpy, MW 0.6 0.6 1.1 −1 0.2 0 −0.9 0.1 −0.9 MW, g/mol 56.7 56.7 47.247.2 28.1 28.1 51.4 42.1 58.1 Density, kg/m³ 0.84 0.84 0.7 606.3 438 438468.4 477.4 465.7 COMPONENTS, wt. % Ethylene 0.0 0.0 10.8 10.8 99.1 99.10.1 0.2 0.0 Propylene 0.0 0.0 30.9 30.9 0.9 0.9 34.6 99.5 0.5 Propane0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 4.4 4.4 0.0 0.0 5.00.1 7.5 Isobutene 0.0 0.0 9.3 9.3 0.0 0.0 10.4 0.2 15.8 cis-2-butene35.0 35.0 4.4 4.4 0.0 0.0 4.9 0.0 7.5 trans-2-butene 35.0 35.0 5.3 5.30.0 0.0 6.0 0.0 9.1 n-Butane 30.0 30.0 30.0 30.0 0.0 0.0 33.7 0.0 51.31-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.3 0.0 0.4 cis-2-Pentene 0.0 0.0 0.30.3 0.0 0.0 0.4 0.0 0.5 trans-2-Pentene 0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.01.1 2-Methyl-2-butene 0.0 0.0 1.5 1.5 0.0 0.0 1.7 0.0 2.63-Methyl-1-butene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 2-Methyl-1-butene0.0 0.0 0.8 0.8 0.0 0.0 0.9 0.0 1.4 Sum of pentenes, 0.0 0.0 1.1 1.1 0.00.0 1.3 0.0 1.9 pentanes, hexenes, hexanes, and heavier Total wt. % 100100 100 100 100 100 100 100 100

TABLE 2 FIG. 1 with 100% Efficiency in mol % Stream Number 201A 201D203A 203B 204 205 206 207 208 Mole Flow, kmol/hr 100 100 120.2 120.219.7 2.2 98.3 41.3 57 Mass Flow, kg/hr 5670 5670 5670 5670 555 62 50531738 3315 Volume Flow m³/hr 6750 6750 8119 9.4 1.3 0.1 10.8 3.6 7.1Enthalpy, MW 0.6 0.6 1.1 −1 0.2 0 −0.9 0.1 −0.9 MW, g/mol 56.7 56.7 47.247.2 28.1 28.1 51.4 42.1 58.1 Density, kg/m³ 0.84 0.84 0.7 606.3 438 438468.4 477.4 465.7 COMPONENTS, mol. % Ethylene 0.0 0.0 18.2 18.2 99.499.4 0.1 0.3 0.0 Propylene 0.0 0.0 34.6 34.6 0.6 0.6 42.2 99.5 0.7Propane 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.7 3.7 0.00.0 4.6 0.1 7.8 Isobutene 0.0 0.0 7.8 7.8 0.0 0.0 9.5 0.2 16.3cis-2-butene 35.4 35.4 3.7 3.7 0.0 0.0 4.5 0.0 7.8 trans-2-butene 35.435.4 4.5 4.5 0.0 0.0 5.5 0.0 9.4 n-Butane 29.3 29.3 24.3 24.3 0.0 0.029.8 0.0 51.3 1-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3cis-2-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.3 0.0 0.4 trans-2-Pentene 0.00.0 0.4 0.4 0.0 0.0 0.5 0.0 0.9 2-Methyl-2-butene 0.0 0.0 1.0 1.0 0.00.0 1.2 0.0 2.1 3-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.2 0.0 0.32-Methyl-1-butene 0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.0 1.2 Sum of pentenes,0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.0 1.3 pentanes, hexenes, hexanes, andheavier Total mol. % 100 100 100 100 100 100 100 100 100

TABLE 3 FIG. 1 with 80% Efficiency in wt. % Stream Number 201A 201D 203A203B 204 205 206 207 208 Mole Flow, kmol/hr 100 100 116.2 116.2 15.8 1.898.6 33 65.6 Mass Flow, kg/hr 5670 5670 5670 5670 444 49 5176 1390 3786Volume Flow m³/hr 6749.8 6749.8 7845 9.2 1 0.1 11.1 2.9 8.1 Enthalpy, MW0.6 0.6 1 −1.1 0.1 0 −0.9 0 −1 MW, g/mol 56.7 56.7 48.8 48.8 28.1 28.152.5 42.1 57.7 Density, kg/m³ 0.84 0.84 0.72 616.1 438 438.1 467.4 477.4467.7 COMPONENTS, wt. % Ethylene 0.0 0.0 8.7 8.7 99.1 99.1 0.0 0.2 0.0Propylene 0.0 0.0 24.7 24.7 0.9 0.9 27.0 99.5 0.4 Propane 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.5 3.5 0.0 0.0 3.9 0.1 5.3Isobutene 0.0 0.0 7.4 7.4 0.0 0.0 8.1 0.2 11.0 cis-2-butene 35.0 35.010.5 10.5 0.0 0.0 11.5 0.0 15.8 trans-2-butene 35.0 35.0 11.3 11.3 0.00.0 12.3 0.0 16.9 n-Butane 30.0 30.0 30.0 30.0 0.0 0.0 32.9 0.0 44.91-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 cis-2-Pentene 0.0 0.0 0.30.3 0.0 0.0 0.3 0.0 0.4 trans-2-Pentene 0.0 0.0 0.5 0.5 0.0 0.0 0.5 0.00.7 2-Methyl-2-butene 0.0 0.0 1.2 1.2 0.0 0.0 1.3 0.0 1.83-Methyl-1-butene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.2 2-Methyl-1-butene0.0 0.0 0.7 0.7 0.0 0.0 0.7 0.0 1.0 Sum of pentenes, 0.0 0.0 1.0 1.0 0.00.0 1.0 0.0 1.3 pentanes, hexenes, hexanes, and heavier Total wt. % 100100 100 100 100 100 100 100 100

TABLE 4 FIG. 1 with 80% Efficiency in mol % Stream Number 201A 201D 203A203B 204 205 206 207 208 Mole Flow, kmol/hr 100 100 116.2 116.2 15.8 1.898.6 33 65.6 Mass Flow, kg/hr 5670 5670 5670 5670 444 49 5176 1390 3786Volume Flow m³/hr 6750 6750 7845 9.2 1 0.1 11.1 2.9 8.1 Enthalpy, MW 0.60.6 1 −1.1 0.1 0 −0.9 0 −1 MW, g/mol 56.7 56.7 48.8 48.8 28.1 28.1 52.542.1 57.7 Density, kg/m³ 0.84 0.84 0.72 616.1 438 438.1 467.4 477.4467.7 COMPONENTS, mol % Ethylene 0.0 0.0 15.1 15.1 99.4 99.4 0.1 0.3 0.0Propylene 0.0 0.0 28.7 28.7 0.6 0.6 33.7 99.5 0.5 Propane 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.1 3.1 0.0 0.0 3.6 0.1 5.4Isobutene 0.0 0.0 6.5 6.5 0.0 0.0 7.6 0.2 11.4 cis-2-butene 35.4 35.49.2 9.2 0.0 0.0 10.8 0.0 16.2 trans-2-butene 35.4 35.4 9.8 9.8 0.0 0.011.5 0.0 17.3 n-Butane 29.3 29.3 25.2 25.2 0.0 0.0 29.7 0.0 44.61-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.2 0.0 0.2 cis-2-Pentene 0.0 0.0 0.20.2 0.0 0.0 0.2 0.0 0.3 trans-2-Pentene 0.0 0.0 0.3 0.3 0.0 0.0 0.4 0.00.6 2-Methyl-2-butene 0.0 0.0 0.8 0.8 0.0 0.0 1.0 0.0 1.53-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.2 2-Methyl-1-butene0.0 0.0 0.5 0.5 0.0 0.0 0.5 0.0 0.8 Sum of pentenes, 0.0 0.0 0.5 0.5 0.00.0 0.5 0.0 1.0 pentanes, hexenes, hexanes, and heavier Total mol % 100100 100 100 100 100 100 100 100

Example 2

The systems of FIG. 2 were also computer modeled using Aspen Plus®. Thesubsequent tables (Tables 5-8) depict the stream compositions as well asthermal properties for selected streams. The system inlet streamcomposition and catalyst reaction rates used for the model were the sameas those of Example 2. The stream number corresponds with the stream orstream segment shown in FIG. 2. Simulations were run for 100% efficiencyand 80% efficiency. Additionally, data is provided on a weight basis anda mole basis for each simulation. Table 5 depicts data for a simulationof the system of FIG. 2 with 100% efficiency and shows components on amass basis. Table 6 depicts data for a simulation of the system of FIG.2 with 100% efficiency and shows components on a mole basis. Table 7depicts data for a simulation of the system of FIG. 2 with 80%efficiency and shows components on a mass basis. Table 8 depicts datafor a simulation of the system of FIG. 2 with 80% efficiency and showscomponents on a mole basis. Additionally, FIG. 8 depicts a bar graphdisplaying the product distribution of the system of FIG. 2 as shown inTable 5 where, on the bar graph, “Propylene” corresponds with the streamof transfer line 307, “Ethylene” corresponds with the stream of transferline 305, “Light Purge” corresponds with the stream of transfer line304, “C4 Purge” corresponds with the stream of transfer line 316, and“C5+Heavy” corresponds with the stream of transfer line 314. The productdistribution of FIG. 8 are based on the Aspen simulations of Table 5.

TABLE 5 FIG. 2 with 100% Efficiency in wt. % Stream Number 310 301D 303A303B 304 305 306 307 308 312 316 314 Mole Flow, kmol/hr 100 270 298 29827.9 3.1 267 58 209 170 19 20 Mass Flow, kg/hr 5670 15469 15469 15469785 87 14597 2452 12144 9799 1089 1256 Volumn Flow m3/hr 6750 1041614771 25 1.8 0.2 32.2 5.1 26.6 20 2.2 2.5 Enthalpy, MW 0.6 −3.5 −1.7−5.5 0.2 0 −4.8 0.1 −4.9 −4.1 −0.5 −0.4 MW, g/mol 56.7 57.4 51.9 51.928.1 28.2 54.6 42.1 58.1 57.7 57.7 61.7 Density, kg/m3 0.84 1.49 1.05618.8 438.1 438.1 453.5 477.4 456.5 490.6 490.6 496.3 COMPONENTS, wt. %Ethylene 0.0 0.0 5.6 5.6 99.0 99.0 0.0 0.2 0.0 0.0 0.0 0.0 Propylene 0.00.1 16.0 16.0 1.0 1.0 16.9 99.5 0.2 0.2 0.2 0.0 Propane 0.0 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 2.0 2.3 2.3 0.0 0.0 2.4 0.12.9 3.2 3.2 0.2 Isobutene 0.0 4.3 4.8 4.8 0.0 0.0 5.1 0.2 6.1 6.7 6.70.3 cis-2-butene 35.0 14.6 2.3 2.3 0.0 0.0 2.4 0.0 2.9 2.7 2.7 4.3trans-2-butene 35.0 15.1 2.8 2.8 0.0 0.0 2.9 0.0 3.5 3.6 3.6 2.6n-Butane 30.0 63.8 63.8 63.8 0.0 0.0 67.6 0.1 81.2 83.3 83.3 63.01-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.2 0.0 0.0 1.4 cis-2-Pentene0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.2 0.0 0.0 2.0 trans-2-Pentene 0.0 0.00.3 0.3 0.0 0.0 0.3 0.0 0.4 0.0 0.0 3.9 2-Methyl-2-butene 0.0 0.0 0.80.8 0.0 0.0 0.8 0.0 1.0 0.0 0.0 9.5 3-Methyl-1-butene 0.0 0.0 0.1 0.10.0 0.0 0.1 0.0 0.1 0.0 0.0 0.9 2-Methyl-1-butene 0.0 0.0 0.4 0.4 0.00.0 0.5 0.0 0.5 0.0 0.0 4.9 Sum of pentenes, 0.0 0.0 0.5 0.5 0.0 0.0 0.50.0 0.7 0.0 0.0 7.1 pentanes, hexenes, hexanes, and heavier Total wt. %100 100 100 100 100 100 100 100 100 100 100 100

TABLE 6 FIG. 2 with 100% Efficiency in mol % Stream Number 310 301D 303A303B 304 305 306 307 308 312 316 314 Mole Flow, kmol/hr 100 270 298 29827.9 3.1 267 58 209 170 19 20 Mass Flow, kg/hr 5670 15469 15469 15469785 87 14597 2452 12144 9799 1089 1256 Volumn Flow m3/hr 6750 1041614771 25 1.8 0.2 32.2 5.1 26.6 20 2.2 2.5 Enthalpy, MW 0.6 −3.5 −1.7−5.5 0.2 0 −4.8 0.1 −4.9 −4.1 −0.5 −0.4 MW, g/mol 56.7 57.4 51.9 51.928.1 28.2 54.6 42.1 58.1 57.7 57.7 61.7 Density, kg/m3 0.84 1.49 1.05618.8 438.1 438.1 453.5 477.4 456.5 490.6 490.6 496.3 COMPONENTS, mol %Ethylene 0.0 0.0 10.4 10.4 99.3 99.3 0.1 0.3 0.0 0.0 0.0 0.0 Propylene0.0 0.2 19.7 19.7 0.7 0.7 21.9 99.5 0.3 0.3 0.3 0.0 Propane 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 2.1 2.1 2.1 0.0 0.0 2.40.0 3.0 3.3 3.3 0.2 Isobutene 0.0 4.4 4.4 4.4 0.0 0.0 5.0 0.1 6.3 6.96.9 0.4 cis-2-butene 35.4 14.9 2.1 2.1 0.0 0.0 2.4 0.0 3.0 2.8 2.8 4.8trans-2-butene 35.4 15.5 2.6 2.6 0.0 0.0 2.8 0.0 3.6 3.7 3.7 2.8n-Butane 29.3 62.9 56.9 56.9 0.0 0.0 63.5 0.1 81.2 82.8 82.8 66.91-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.0 0.0 1.2 cis-2-Pentene0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.2 0.0 0.0 1.7 trans-2-Pentene 0.0 0.00.2 0.2 0.0 0.0 0.3 0.0 0.3 0.0 0.0 3.4 2-Methyl-2-butene 0.0 0.0 0.60.6 0.0 0.0 0.6 0.0 0.8 0.0 0.0 8.4 3-Methyl-1-butene 0.0 0.0 0.1 0.10.0 0.0 0.1 0.0 0.1 0.0 0.0 0.8 2-Methyl-1-butene 0.0 0.0 0.3 0.3 0.00.0 0.4 0.0 0.5 0.0 0.0 4.3 Sum of pentenes, 0.0 0.0 0.3 0.3 0.0 0.0 0.50.0 0.5 0.0 0.0 5.0 pentanes, hexenes, hexanes, and heavier Total mol %100 100 100 100 100 100 100 100 100 100 100 100

TABLE 7 FIG. 2 with 80% Efficiency in wt. % Stream Number 310 301D 303A303B 304 305 306 307 308 312 316 314 Mole Flow, kmol/hr 100 318 345 34526.5 2.9 316 55 260 218 24 18 Mass Flow, kg/hr 5670 18231 18231 18231746 83 17403 2334 15069 12562 1396 1112 Volumn Flow m3/hr 6750 1129015751 29.2 1.7 0.2 38.5 4.9 32.9 25.5 2.8 2.2 Enthalpy, MW 0.6 −4.4 −2.7−6.6 0.2 0 −5.6 0.1 −5.7 −5 −0.6 −0.4 MW, g/mol 56.7 57.4 52.9 52.9 28.128.2 55.2 42.1 57.9 57.7 57.7 61.8 Density, kg/m3 0.84 1.61 1.16 623.6438.1 438.1 452 477.4 457.7 492 492 499.4 COMPONENTS, wt. % Ethylene 0.00.0 4.5 4.5 99.0 99.0 0.0 0.2 0.0 0.0 0.0 0.0 Propylene 0.0 0.1 12.912.9 1.0 1.0 13.5 99.5 0.2 0.2 0.2 0.0 Propane 0.0 0.0 0.0 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 2.0 2.2 2.2 0.0 0.0 2.4 0.1 2.7 2.92.9 0.1 Isobutene 0.0 4.2 4.7 4.7 0.0 0.0 4.9 0.2 5.7 6.1 6.1 0.2cis-2-butene 35.0 14.7 4.8 4.8 0.0 0.0 5.0 0.0 5.8 5.5 5.5 9.3trans-2-butene 35.0 15.4 5.3 5.3 0.0 0.0 5.6 0.0 6.4 6.6 6.6 4.3n-Butane 30.0 63.5 63.5 63.5 0.0 0.0 66.5 0.1 76.8 78.6 78.6 54.11-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.0 0.0 1.5 cis-2-Pentene0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.2 0.0 0.0 2.1 trans-2-Pentene 0.0 0.00.3 0.3 0.0 0.0 0.3 0.0 0.3 0.0 0.0 4.2 2-Methyl-2-butene 0.0 0.0 0.60.6 0.0 0.0 0.7 0.0 0.8 0.0 0.0 10.3 3-Methyl-1-butene 0.0 0.0 0.1 0.10.0 0.0 0.1 0.0 0.1 0.0 0.0 1.0 2-Methyl-1-butene 0.0 0.0 0.4 0.4 0.00.0 0.4 0.0 0.4 0.0 0.0 5.3 Sum of pentenes, 0.0 0.0 0.5 0.5 0.0 0.0 0.50.0 0.5 0.0 0.0 7.5 pentanes, hexenes, hexanes, and heavier Total wt. %100 100 100 100 100 100 100 100 100 100 100 100

TABLE 8 FIG. 2 with 80% Efficiency in mol % Stream Number 310 301D 303A303B 304 305 306 307 308 312 316 314 Mole Flow, kmol/hr 100 318 345 34526 3 316 55 260 218 24 18 Mass Flow, kg/hr 5670 18231 18231 18231 746 8317403 2334 15069 12562 1396 1112 Volumn Flow m3/hr 6750 11290 15751 29.21.7 0.2 38.5 4.9 32.9 25.5 2.8 2.2 Enthalpy, MW 0.6 −4.4 −2.7 −6.6 0.2 0−5.6 0.1 −5.7 −5 −0.6 −0.4 MW, g/mol 56.7 57.4 52.9 52.9 28.1 28.2 55.242.1 57.9 57.7 57.7 61.8 Density, kg/m3 0.84 1.61 1.16 623.6 438.1 438.1452 477.4 457.7 492 492 499.4 COMPONENTS, mol % Ethylene 0.0 0.0 8.5 8.599.3 99.3 0.0 0.3 0.0 0.0 0.0 0.0 Propylene 0.0 0.2 16.2 16.2 0.7 0.717.7 99.5 0.2 0.2 0.2 0.0 Propane 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.00.0 0.0 0.0 1-Butene 0.0 2.1 2.1 2.1 0.0 0.0 2.3 0.0 2.8 3.0 3.0 0.1Isobutene 0.0 4.3 4.4 4.4 0.0 0.0 4.9 0.1 5.9 6.3 6.3 0.2 cis-2-butene35.4 15.0 4.5 4.5 0.0 0.0 4.9 0.0 6.0 5.6 5.6 10.3 trans-2-butene 35.415.8 5.0 5.0 0.0 0.0 5.5 0.0 6.6 6.8 6.8 4.7 n-Butane 29.3 62.7 57.757.7 0.0 0.0 63.1 0.1 76.6 78.0 78.0 57.6 1-Pentene 0.0 0.0 0.1 0.1 0.00.0 0.1 0.0 0.1 0.0 0.0 1.4 cis-2-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.10.0 0.1 0.0 0.0 1.9 trans-2-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.30.0 0.0 3.7 2-Methyl-2-butene 0.0 0.0 0.5 0.5 0.0 0.0 0.5 0.0 0.6 0.00.0 9.0 3-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.0 0.00.8 2-Methyl-1-butene 0.0 0.0 0.3 0.3 0.0 0.0 0.3 0.0 0.4 0.0 0.0 4.7Sum of pentenes, 0.0 0.0 0.3 0.3 0.0 0.0 0.3 0.0 0.5 0.0 0.0 5.7pentanes, hexenes, hexanes, and heavier Total mol % 100 100 100 100 100100 100 100 100 100 100 100

Example 3

The systems of FIG. 3 were also computer modeled using Aspen Plus®. Thesubsequent tables (Tables 9-12) depict the stream compositions as wellas thermal properties for selected streams. The system inlet streamcomposition and catalyst reaction rates used for the model were the sameas those of Example 1. The stream number corresponds with the stream orstream segment shown in FIG. 3. Simulations were run for 100% efficiencyand 80% efficiency. Additionally, data is provided on a weight basis anda mole basis for each simulation. Table 9 depicts data for a simulationof the system of FIG. 3 with 100% efficiency and shows components on amass basis. Table 10 depicts data for a simulation of the system of FIG.3 with 100% efficiency and shows components on a mole basis. Table 11depicts data for a simulation of the system of FIG. 3 with 80%efficiency and shows components on a mass basis. Table 12 depicts datafor a simulation of the system of FIG. 3 with 80% efficiency and showscomponents on a mole basis. Additionally, FIG. 9 depicts a bar graphdisplaying the product distribution of the system of FIG. 3 as shown inTable 9 where, on the bar graph, “Propylene” corresponds with the streamof transfer line 407, “Ethylene” corresponds with the stream of transferline 405, “Light Purge” corresponds with the stream of transfer line404, and “C4/C5+Heavy” corresponds with the stream of transfer line 408.The product distribution of FIG. 9 are based on the Aspen simulations ofTable 9.

TABLE 9 FIG. 3 with 100% Efficiency in wt. % Stream Number 401A 401D403A 403B 404 405 406 407 408 Mole Flow, kmol/hr 100 100 120.2 120.219.7 2.2 98.3 41.3 57 Mass Flow, kg/hr 5670 5670 5670 5670 555 62 50531738 3315 Volume Flow m³/hr 6750 6750 8119 9.4 1.3 0.1 10.8 3.6 7.1Enthalpy, MW 0.6 0.6 1.1 −1 0.2 0 −0.9 0.1 −0.9 MW, g/mol 56.7 56.7 47.247.2 28.1 28.1 51.4 42.1 58.1 Density, kg/m³ 0.84 0.84 0.7 606.3 438 438468.4 477.4 465.7 COMPONENTS, wt. % Ethylene 0.0 0.0 10.8 10.8 99.1 99.10.1 0.2 0.0 Propylene 0.0 0.0 30.9 30.9 0.9 0.9 34.6 99.5 0.5 Propane0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 4.4 4.4 0.0 0.0 5.00.1 7.5 Isobutene 0.0 0.0 9.3 9.3 0.0 0.0 10.4 0.2 15.8 cis-2-butene35.0 35.0 4.4 4.4 0.0 0.0 4.9 0.0 7.5 trans-2-butene 35.0 35.0 5.3 5.30.0 0.0 6.0 0.0 9.1 n-Butane 30.0 30.0 30.0 30.0 0.0 0.0 33.7 0.0 51.31-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.3 0.0 0.4 cis-2-Pentene 0.0 0.0 0.30.3 0.0 0.0 0.4 0.0 0.5 trans-2-Pentene 0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.01.1 2-Methyl-2-butene 0.0 0.0 1.5 1.5 0.0 0.0 1.7 0.0 2.63-Methyl-1-butene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 2-Methyl-1-butene0.0 0.0 0.8 0.8 0.0 0.0 0.9 0.0 1.4 Sum of pentenes, 0.0 0.0 1.1 1.1 0.00.0 1.3 0.0 1.9 pentanes, hexenes, hexanes, and heavier Total wt. % 100100 100 100 100 100 100 100 100

TABLE 10 FIG. 3 with 100% Efficiency in mol % Stream Number 401A 401D403A 403B 404 405 406 407 408 Mole Flow, kmol/hr 100 100 120.2 120.219.7 2.2 98.3 41.3 57 Mass Flow, kg/hr 5670 5670 5670 5670 555 62 50531738 3315 Volume Flow m³/hr 6750 6750 8119 9.4 1.3 0.1 10.8 3.6 7.1Enthalpy, MW 0.6 0.6 1.1 −1 0.2 0 −0.9 0.1 −0.9 MW, g/mol 56.7 56.7 47.247.2 28.1 28.1 51.4 42.1 58.1 Density, kg/m³ 0.84 0.84 0.7 606.3 438 438468.4 477.4 465.7 COMPONENTS, mol % Ethylene 0.0 0.0 18.2 18.2 99.4 99.40.1 0.3 0.0 Propylene 0.0 0.0 34.6 34.6 0.6 0.6 42.2 99.5 0.7 Propane0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.7 3.7 0.0 0.0 4.60.1 7.8 Isobutene 0.0 0.0 7.8 7.8 0.0 0.0 9.5 0.2 16.3 cis-2-butene 35.435.4 3.7 3.7 0.0 0.0 4.5 0.0 7.8 trans-2-butene 35.4 35.4 4.5 4.5 0.00.0 5.5 0.0 9.4 n-Butane 29.3 29.3 24.3 24.3 0.0 0.0 29.8 0.0 51.31-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 cis-2-Pentene 0.0 0.0 0.20.2 0.0 0.0 0.3 0.0 0.4 trans-2-Pentene 0.0 0.0 0.4 0.4 0.0 0.0 0.5 0.00.9 2-Methyl-2-butene 0.0 0.0 1.0 1.0 0.0 0.0 1.2 0.0 2.13-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.2 0.0 0.3 2-Methyl-1-butene0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.0 1.2 Sum of pentenes, 0.0 0.0 0.6 0.6 0.00.0 0.7 0.0 1.3 pentanes, hexenes, hexanes, and heavier Total mol % 100100 100 100 100 100 100 100 100

TABLE 11 FIG. 3 with 80% Efficiency in wt. % Stream Number 401A 401D403A 403B 404 405 406 407 408 Mole Flow, kmol/hr 100 100 120.2 120.219.7 2.2 98.3 41.3 57 Mass Flow, kg/hr 5670 5670 5670 5670 555 62 50531738 3315 Volume Flow m³/hr 6750 6750 8119 9.4 1.3 0.1 10.8 3.6 7.1Enthalpy, MW 0.6 0.6 1.1 −1 0.2 0 −0.9 0.1 −0.9 MW, g/mol 56.7 56.7 47.247.2 28.1 28.1 51.4 42.1 58.1 Density, kg/m³ 0.84 0.84 0.7 606.3 438 438468.4 477.4 465.7 COMPONENTS, mol % Ethylene 0.0 0.0 18.2 18.2 99.4 99.40.1 0.3 0.0 Propylene 0.0 0.0 34.6 34.6 0.6 0.6 42.2 99.5 0.7 Propane0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.7 3.7 0.0 0.0 4.60.1 7.8 Isobutene 0.0 0.0 7.8 7.8 0.0 0.0 9.5 0.2 16.3 cis-2-butene 35.435.4 3.7 3.7 0.0 0.0 4.5 0.0 7.8 trans-2-butene 35.4 35.4 4.5 4.5 0.00.0 5.5 0.0 9.4 n-Butane 29.3 29.3 24.3 24.3 0.0 0.0 29.8 0.0 51.31-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 cis-2-Pentene 0.0 0.0 0.20.2 0.0 0.0 0.3 0.0 0.4 trans-2-Pentene 0.0 0.0 0.4 0.4 0.0 0.0 0.5 0.00.9 2-Methyl-2-butene 0.0 0.0 1.0 1.0 0.0 0.0 1.2 0.0 2.13-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.2 0.0 0.3 2-Methyl-1-butene0.0 0.0 0.6 0.6 0.0 0.0 0.7 0.0 1.2 Sum of pentenes, 0.0 0.0 0.6 0.6 0.00.0 0.7 0.0 1.3 pentanes, hexenes, hexanes, and heavier Total mol % 100100 100 100 100 100 100 100 100

TABLE 12 FIG. 3 with 80% Efficiency in mol % Stream Number 401A 401D403A 403B 404 405 406 407 408 Mole Flow, kmol/hr 100 100 116.2 116.215.8 1.8 98.6 33 65.6 Mass Flow, kg/hr 5670 5670 5670 5670 444 49 51761390 3786 Volume Flow m³/hr 6750 6750 7845 9.2 1 0.1 11.1 2.9 8.1Enthalpy, MW 0.6 0.6 1 −1.1 0.1 0 −0.9 0 −1 MW, g/mol 56.7 56.7 48.848.8 28.1 28.1 52.5 42.1 57.7 Density, kg/m³ 0.84 0.84 0.72 616.1 438438.1 467.4 477.4 467.7 COMPONENTS, mol % Ethylene 0.0 0.0 15.1 15.199.4 99.4 0.1 0.3 0.0 Propylene 0.0 0.0 28.7 28.7 0.6 0.6 33.7 99.5 0.5Propane 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.1 3.1 0.00.0 3.6 0.1 5.4 Isobutene 0.0 0.0 6.5 6.5 0.0 0.0 7.6 0.2 11.4cis-2-butene 35.4 35.4 9.2 9.2 0.0 0.0 10.8 0.0 16.2 trans-2-butene 35.435.4 9.8 9.8 0.0 0.0 11.5 0.0 17.3 n-Butane 29.3 29.3 25.2 25.2 0.0 0.029.7 0.0 44.6 1-Pentene 0.0 0.0 0.1 0.1 0.0 0.0 0.2 0.0 0.2cis-2-Pentene 0.0 0.0 0.2 0.2 0.0 0.0 0.2 0.0 0.3 trans-2-Pentene 0.00.0 0.3 0.3 0.0 0.0 0.4 0.0 0.6 2-Methyl-2-butene 0.0 0.0 0.8 0.8 0.00.0 1.0 0.0 1.5 3-Methyl-1-butene 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.22-Methyl-1-butene 0.0 0.0 0.5 0.5 0.0 0.0 0.5 0.0 0.8 Sum of pentenes,0.0 0.0 0.5 0.5 0.0 0.0 0.5 0.0 1.0 pentanes, hexenes, hexanes, andheavier Total mol % 100 100 100 100 100 100 100 100 100

Example 4

The systems of FIG. 4 were also computer modeled using Aspen Plus®. Thesubsequent tables (Tables 13-16) depict the stream compositions as wellas thermal properties for selected streams. The system inlet streamcomposition and catalyst reaction rates used for the model were the sameas those of Example 1. The stream number corresponds with the stream orstream segment shown in FIG. 4. Simulations were run for 100% efficiencyand 80% efficiency. Additionally, data is provided on a weight basis anda mole basis for each simulation. Table 13 depicts data for a simulationof the system of FIG. 4 with 100% efficiency and shows components on amass basis. Table 14 depicts data for a simulation of the system of FIG.4 with 100% efficiency and shows components on a mole basis. Table 15depicts data for a simulation of the system of FIG. 4 with 80%efficiency and shows components on a mass basis. Table 16 depicts datafor a simulation of the system of FIG. 4 with 80% efficiency and showscomponents on a mole basis. Additionally, FIG. 10 depicts a bar graphdisplaying the product distribution of the system of FIG. 4 as shown inTable 13 where, on the bar graph, “Propylene” corresponds with thestream of transfer line 507, “Ethylene” corresponds with the stream oftransfer line 505, “Light Purge” corresponds with the stream of transferline 504, “C4 Purge” corresponds with the stream of transfer line 516,and “C5+Heavy” corresponds with the stream of transfer line 514. Theproduct distribution of FIG. 10 are based on the Aspen simulations ofTable 13.

TABLE 13 FIG. 4 with 100% Efficiency in wt. % Stream Number 501A 501D510 503A 503B 504 505 506 507 508 512 516 514 Mole Flow, kmol/hr 100 100120 528 528 27 3 499 52 446 402 37 8 Mass Flow, kg/hr 5670 5670 567029468 29468 741 82 28644 2202 26443 23799 2098 547 Volume Flow m³/hr6750 6750 8119 1310 47.9 1.7 0.2 62.3 4.6 56.1 57.4 4.2 1 Enthalpy, MW0.6 0.6 1.1 0.6 −10.3 0.2 0 −8.8 0 −8.9 −8.3 −0.8 −0.2 MW, g/mol 56.756.7 47.2 55.8 55.8 27.8 27.9 57.5 42.1 59.3 59.3 57.4 67.4 Density,kg/m³ 0.84 0.84 0.7 22.49 615.4 439.9 440 460 477.3 471 414.8 493.8544.2 COMPONENTS, wt. % Methane 0.0 0.0 0.0 0.1 0.1 1.9 1.9 0.0 0.0 0.00.0 0.0 0.0 Ethane 0.0 0.0 0.0 0.0 0.0 0.2 0.2 0.0 0.3 0.0 0.0 0.0 0.0Ethylene 0.0 0.0 18.2 5.5 5.5 97.8 97.8 0.0 0.3 0.0 0.0 0.0 0.0Propylene 0.0 0.0 34.6 9.8 9.8 0.1 0.1 10.4 97.1 0.2 0.2 0.3 0.0 Propane0.0 0.0 0.0 0.2 0.2 0.0 0.0 0.2 1.7 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.71.1 1.1 0.0 0.0 1.1 0.0 1.3 1.3 1.5 0.3 Isobutene 0.0 0.0 7.8 20.0 20.00.0 0.0 21.2 0.6 23.7 23.7 27.9 4.5 cis-2-butene 35.4 35.4 3.7 0.9 0.90.0 0.0 1.0 0.0 1.1 1.1 1.0 1.5 trans-2-butene 35.4 35.4 4.5 1.1 1.1 0.00.0 1.2 0.0 1.4 1.4 1.4 1.2 n-Butane 29.3 29.3 24.3 56.4 56.4 0.0 0.059.8 0.0 66.8 66.8 67.8 61.8 1-Pentene 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.10.0 0.2 0.2 0.0 0.8 cis-2-Pentene 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.1 0.00.1 0.1 0.0 0.3 trans-2-Pentene 0.0 0.0 0.4 0.1 0.1 0.0 0.0 0.1 0.0 0.10.1 0.0 0.7 2-Methyl-2-butene 0.0 0.0 1.0 0.2 0.2 0.0 0.0 0.3 0.0 0.30.3 0.0 1.6 3-Methyl-1-butene 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.10.1 0.0 0.2 2-Methyl-1-butene 0.0 0.0 0.6 0.1 0.1 0.0 0.0 0.1 0.0 0.20.2 0.0 0.8 2-Methy-butane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.10.0 0.3 n-Pentane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.1 0.0 0.4Sum of pentenes, 0.0 0.0 0.6 3.9 3.9 0.0 0.0 4.3 0.0 4.6 4.6 0.0 25.5pentanes, hexenes, hexanes, and heavier Total wt. % 100 100 100 100 100100 100 100 100 100 100 100 100

TABLE 14 FIG. 4 with 100% Efficiency in mol % Stream Number 501A 501D510 503A 503B 504 505 506 507 508 512 516 514 Mole Flow, kmol/hr 100 100120 528 528 27 3 499 52 446 402 37 8 Mass Flow, kg/hr 5670 5670 567029468 29468 741 82 28644 2202 26443 23799 2098 547 Volume Flow m³/hr6750 6750 8119 1310 47.9 1.7 0.2 62.3 4.6 56.1 57.4 4.2 1 Enthalpy, MW0.6 0.6 1.1 0.6 −10.3 0.2 0 −8.8 0 −8.9 −8.3 −0.8 −0.2 MW, g/mol 56.756.7 47.2 55.8 55.8 27.8 27.9 57.5 42.1 59.3 59.3 57.4 67.4 Density,kg/m³ 0.84 0.84 0.7 22.49 615.4 439.9 440 460 477.3 471 414.8 493.8544.2 COMPONENTS, mol % Methane 0.0 0.0 0.0 0.1 0.1 1.9 1.9 0.0 0.0 0.00.0 0.0 0.0 Ethane 0.0 0.0 0.0 0.0 0.0 0.2 0.2 0.0 0.3 0.0 0.0 0.0 0.0Ethylene 0.0 0.0 18.2 5.5 5.5 97.8 97.8 0.0 0.3 0.0 0.0 0.0 0.0Propylene 0.0 0.0 34.6 9.8 9.8 0.1 0.1 10.4 97.1 0.2 0.2 0.3 0.0 Propane0.0 0.0 0.0 0.2 0.2 0.0 0.0 0.2 1.7 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.71.1 1.1 0.0 0.0 1.1 0.0 1.3 1.3 1.5 0.3 Isobutene 0.0 0.0 7.8 20.0 20.00.0 0.0 21.2 0.6 23.7 23.7 27.9 4.5 cis-2-butene 35.4 35.4 3.7 0.9 0.90.0 0.0 1.0 0.0 1.1 1.1 1.0 1.5 trans-2-butene 35.4 35.4 4.5 1.1 1.1 0.00.0 1.2 0.0 1.4 1.4 1.4 1.2 n-Butane 29.3 29.3 24.3 56.4 56.4 0.0 0.059.8 0.0 66.8 66.8 67.8 61.8 1-Pentene 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.10.0 0.2 0.2 0.0 0.8 cis-2-Pentene 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.1 0.00.1 0.1 0.0 0.3 trans-2-Pentene 0.0 0.0 0.4 0.1 0.1 0.0 0.0 0.1 0.0 0.10.1 0.0 0.7 2-Methyl-2-butene 0.0 0.0 1.0 0.2 0.2 0.0 0.0 0.3 0.0 0.30.3 0.0 1.6 3-Methyl-1-butene 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.10.1 0.0 0.2 2-Methyl-1-butene 0.0 0.0 0.6 0.1 0.1 0.0 0.0 0.1 0.0 0.20.2 0.0 0.8 2-Methy-butane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.10.0 0.3 n-Pentane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.1 0.0 0.4Sum of pentenes, 0.0 0.0 0.6 3.9 3.9 0.0 0.0 4.3 0.0 4.6 4.6 0.0 25.5pentanes, hexenes, hexanes, and heavier Total mol % 100 100 100 100 100100 100 100 100 100 100 100 100

TABLE 15 FIG. 4 with 80% Efficiency in wt. % Stream Number 501A 501D 510503A 503B 504 505 506 507 508 512 516 514 Mole Flow, kmol/hr 100 100 116540 540 27 3 511 50 461 415 39 7 Mass Flow, kg/hr 5670 5670 5670 3043630436 739 82 29616 2096 27519 24767 2218 534 Volume Flow m³/hr 6750 67507845 1220 49 1.7 0.2 63.7 4.4 57.8 63.1 4.5 0.9 Enthalpy, MW 0.6 0.6 1−0.6 −10.4 0.2 0 −8.8 0 −8.9 −8.3 −0.8 −0.1 MW, g/mol 56.7 56.7 48.856.3 56.3 27.7 27.7 58 42.1 59.7 59.7 57.5 71.3 Density, kg/m³ 0.84 0.840.72 24.94 620.7 441.4 441.4 464.8 476.9 476.3 392.4 493.9 572.6COMPONENTS, wt. % Methane 0.0 0.0 0.0 0.0 0.0 1.8 1.8 0.0 0.0 0.0 0.00.0 0.0 Ethane 0.0 0.0 0.0 0.0 0.0 0.2 0.2 0.0 0.4 0.0 0.0 0.0 0.0Ethylene 0.0 0.0 8.7 2.7 2.7 98.0 98.0 0.0 0.2 0.0 0.0 0.0 0.0 Propylene0.0 0.0 24.7 6.7 6.7 0.0 0.0 6.8 95.9 0.1 0.1 0.1 0.0 Propane 0.0 0.00.0 0.2 0.2 0.0 0.0 0.2 3.1 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.5 1.1 1.10.0 0.0 1.1 0.0 1.2 1.2 1.4 0.1 Isobutene 0.0 0.0 7.4 17.7 17.7 0.0 0.018.1 0.3 19.5 19.5 23.7 1.9 cis-2-butene 35.0 35.0 10.5 2.5 2.5 0.0 0.02.6 0.0 2.7 2.7 2.7 2.9 trans-2-butene 35.0 35.0 11.3 2.7 2.7 0.0 0.02.7 0.0 2.9 2.9 3.2 1.9 n-Butane 30.0 30.0 30.0 57.3 57.3 0.0 0.0 58.80.1 63.3 63.3 68.7 40.8 1-Pentene 0.0 0.0 0.2 0.3 0.3 0.0 0.0 0.3 0.00.3 0.3 0.0 1.4 cis-2-Pentene 0.0 0.0 0.3 0.1 0.1 0.0 0.0 0.1 0.0 0.10.1 0.0 0.3 trans-2-Pentene 0.0 0.0 0.5 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.10.0 0.6 2-Methyl-2-butene 0.0 0.0 1.2 0.3 0.3 0.0 0.0 0.3 0.0 0.3 0.30.0 1.6 3-Methyl-1-butene 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.10.0 0.2 2-Methyl-1-butene 0.0 0.0 0.7 0.2 0.2 0.0 0.0 0.2 0.0 0.2 0.20.0 0.9 2-Methy-butane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.1 0.00.3 n-Pentane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.1 0.0 0.4 Sum ofpentenes, 0.0 0.0 1.0 8.1 8.1 0.0 0.0 8.3 0.0 8.9 8.9 0.0 46.5 pentanes,hexenes, hexanes, and heavier Total wt. % 100 100 100 100 100 100 100100 100 100 100 100 100

TABLE 16 FIG. 4 with 80% Efficiency in mol % Stream Number 501A 501D 510503A 503B 504 505 506 507 508 512 516 514 Mole Flow, kmol/hr 100 100 116540 540 27 3 511 50 461 415 39 7 Mass Flow, kg/hr 5670 5670 5670 3043630436 739 82 29616 2096 27519 24767 2218 534 Volume Flow m³/hr 6750 67507845 1220 49 1.7 0.2 63.7 4.4 57.8 63.1 4.5 0.9 Enthalpy, MW 0.6 0.6 1−0.6 −10.4 0.2 0 −8.8 0 −8.9 −8.3 −0.8 −0.1 MW, g/mol 56.7 56.7 48.856.3 56.3 27.7 27.7 58 42.1 59.7 59.7 57.5 71.3 Density, kg/m³ 0.84 0.840.72 24.94 620.7 441.4 441.4 464.8 476.9 476.3 392.4 493.9 572.6COMPONENTS, mol % Methane 0.0 0.0 0.0 0.2 0.2 3.1 3.1 0.0 0.0 0.0 0.00.0 0.0 Ethane 0.0 0.0 0.0 0.1 0.1 0.2 0.2 0.1 0.6 0.0 0.0 0.0 0.0Ethylene 0.0 0.0 15.1 5.3 5.3 96.7 96.7 0.0 0.3 0.0 0.0 0.0 0.0Propylene 0.0 0.0 28.7 8.9 8.9 0.0 0.0 9.4 95.9 0.1 0.1 0.1 0.0 Propane0.0 0.0 0.0 0.3 0.3 0.0 0.0 0.3 2.9 0.0 0.0 0.0 0.0 1-Butene 0.0 0.0 3.11.1 1.1 0.0 0.0 1.1 0.0 1.3 1.3 1.5 0.2 Isobutene 0.0 0.0 6.5 17.7 17.70.0 0.0 18.8 0.2 20.8 20.8 24.3 2.4 cis-2-butene 35.4 35.4 9.2 2.5 2.50.0 0.0 2.6 0.0 2.9 2.9 2.8 3.7 trans-2-butene 35.4 35.4 9.8 2.7 2.7 0.00.0 2.8 0.0 3.1 3.1 3.3 2.4 n-Butane 29.3 29.3 25.2 55.5 55.5 0.0 0.058.7 0.1 65.1 65.1 68.0 50.1 1-Pentene 0.0 0.0 0.1 0.2 0.2 0.0 0.0 0.20.0 0.3 0.3 0.0 1.4 cis-2-Pentene 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.00.1 0.1 0.0 0.3 trans-2-Pentene 0.0 0.0 0.3 0.1 0.1 0.0 0.0 0.1 0.0 0.10.1 0.0 0.7 2-Methyl-2-butene 0.0 0.0 0.8 0.2 0.2 0.0 0.0 0.2 0.0 0.30.3 0.0 1.6 3-Methyl-1-butene 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.1 0.0 0.10.1 0.0 0.3 2-Methyl-1-butene 0.0 0.0 0.5 0.1 0.1 0.0 0.0 0.1 0.0 0.10.1 0.0 0.9 2-Methy-butane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.10.0 0.3 n-Pentane 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.1 0.0 0.1 0.1 0.0 0.4Sum of pentenes, 0.0 0.0 0.5 4.7 4.7 0.0 0.0 5.2 0.0 5.8 5.8 0.0 35.4pentanes, hexenes, hexanes, and heavier Total mol % 100 100 100 100 100100 100 100 100 100 100 100 100

Example 5

Table 17 shows butene conversion, propylene selectivity, and propyleneyield for the embodiments of FIGS. 1-4. The data was determined usingAspen Plus® with the conditions as those provided for Tables 1, 5, 9,and 13.

The butene conversion is defined as:

$\left( {1 - \frac{{Mass}\mspace{14mu} {flow}\mspace{14mu} {of}\mspace{14mu} 2\text{-}{butene}\mspace{14mu} {in}\mspace{14mu} {combined}\mspace{14mu} {reactor}\mspace{14mu} {effluent}}{{Mass}\mspace{14mu} {flow}\mspace{14mu} {of}\mspace{14mu} 2\text{-}{butene}\mspace{14mu} {in}\mspace{14mu} {combined}\mspace{14mu} {reactor}\mspace{14mu} {feed}}} \right)*100$

The propylene selectivity is defined as:

$\left( \frac{\begin{matrix}{{{Mass}\mspace{14mu} {flow}\mspace{14mu} {of}\mspace{14mu} {propylene}\mspace{14mu} {in}\mspace{14mu} {reactor}\mspace{14mu} {effluent}} -} \\{{Mass}\mspace{14mu} {flow}\mspace{14mu} {of}\mspace{14mu} {propylene}\mspace{14mu} {in}\mspace{14mu} {reactor}\mspace{14mu} {feed}}\end{matrix}}{\begin{matrix}{{Mass}\mspace{14mu} {flow}\mspace{14mu} {of}\mspace{14mu} 2\text{-}{butene}\mspace{14mu} {in}\mspace{14mu} {reactor}\mspace{14mu} {feed}*} \\{{butene}\mspace{14mu} {conversion}\mspace{14mu} {rate}}\end{matrix}} \right)*100\%$

The propylene yield is defined as:

$\left( \frac{{Total}\mspace{14mu} {Propylene}\mspace{14mu} {Produced}\mspace{14mu} \left( {{wt}.\mspace{14mu} \%} \right)}{{Total}\mspace{14mu} {butene}\mspace{14mu} 2\mspace{14mu} {in}\mspace{14mu} {Feed}\mspace{14mu} \left( {{wt}.\mspace{14mu} \%} \right)} \right)*100\%$

TABLE 17 Embodiment Embodiment Embodiment Embodiment of FIG. 1 of FIG. 2of FIG. 3 of FIG. 4 Butene 86.1% 83.0% 86.1% 86.3% Conversion Propylene51.3% 64.3% 51.3% 54.8% selectivity Propylene 44.1% 61.8% 44.1% 54.0%yield

For the purposes of describing and defining the present disclosure it isnoted that the term “about” are utilized in this disclosure to representthe inherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “about” are also utilized in this disclosure to represent thedegree by which a quantitative representation may vary from a statedreference without resulting in a change in the basic function of thesubject matter at issue. Additionally, the term “consisting essentiallyof” is used in this disclosure to refer to quantitative values that donot materially affect the basic and novel characteristic(s) of thedisclosure. For example, a chemical stream “consisting essentially” of aparticular chemical constituent or group of chemical constituents shouldbe understood to mean that the stream includes at least about 99.5% of athat particular chemical constituent or group of chemical constituents.

It should be appreciated that compositional ranges of a chemicalconstituent in a stream or in a reactor should be appreciated ascontaining, in some embodiments, a mixture of isomers of thatconstituent. For example, a compositional range specifying butene mayinclude a mixture of various isomers of butene. It should be appreciatedthat the examples supply compositional ranges for various streams, andthat the total amount of isomers of a particular chemical compositioncan constitute a range.

It is noted that one or more of the following claims utilize the term“where” as a transitional phrase. For the purposes of defining thepresent technology, it is noted that this term is introduced in theclaims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should beinterpreted in like manner as the more commonly used open-ended preambleterm “comprising.”

It should be understood that any two quantitative values assigned to aproperty may constitute a range of that property, and all combinationsof ranges formed from all stated quantitative values of a given propertyare contemplated in this disclosure.

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments, it is noted that the variousdetails described in this disclosure should not be taken to imply thatthese details relate to elements that are essential components of thevarious embodiments described in this disclosure, even in cases where aparticular element is illustrated in each of the drawings that accompanythe present description. Rather, the claims appended hereto should betaken as the sole representation of the breadth of the presentdisclosure and the corresponding scope of the various embodimentsdescribed in this disclosure. Further, it will be apparent thatmodifications and variations are possible without departing from thescope of the appended claims.

What is claimed is:
 1. A process for producing propylene, the processcomprising: introducing a first stream comprising butene to a reactor,where the reactor comprises a metathesis catalyst and a crackingcatalyst, the metathesis catalyst positioned generally upstream of thecracking catalyst; at least partially metathesizing the first streamwith the metathesis catalyst to form a metathesis-reaction product; atleast partially cracking the metathesis-reaction product with thecracking catalyst to form a cracking-reaction product comprising butene;passing the cracking-reaction product out of the reactor in acracking-reaction product stream; and at least partially separatingpropylene from the cracking-reaction product stream to form a productstream comprising propylene, where: at least a portion of the butene inthe cracking-reaction product stream is recycled by at least partiallyseparating butene in the cracking-reaction product stream to form arecycle stream comprising butene; and the first stream is a mixture ofthe recycle stream and a system inlet stream.
 2. The process of claim 1,where the first stream comprises at least 20 wt. % butene.
 3. Theprocess of claim 1, where the system inlet stream comprises at least 50wt. % butene.
 4. The process of claim 1, where the recycle streamcomprises at least 80 wt. % of butane and butene.
 5. The process ofclaim 27, where the cracking-reaction product comprises at least 4 wt. %propylene.
 6. The process of claim 1, where the product stream comprisesat least 90 wt. % propylene.
 7. The process of claim 1, where: themetathesis catalyst comprises a mesoporous silica catalyst impregnatedwith metal oxide, where the mesoporous silica catalyst includes a poresize distribution of about 2.5 nm to about 40 nm and a total pore volumeof at least about 0.600 cm³/g; and the cracking catalyst comprises amordenite framework inverted (MFI) structured silica catalyst downstreamof the mesoporous silica catalyst, where the MFI structured silicacatalyst includes total acidity of 0.001 mmol/g to 0.1 mmol/g.
 8. Theprocess of claim 1, where the metathesis catalyst comprises an amorphousmesoporous silica foam impregnated with metal oxides, where themetathesis catalyst has a pore size distribution of at least 3 nm to 40nm and a total pore volume of at least 0.700 cm³/g.
 9. A system forproducing propylene as described in claim
 1. 10. A process for producingpropylene, the process comprising: introducing a first stream comprisingbutene to a first reactor, the first reactor comprising a metathesiscatalyst; at least partially metathesizing the first stream in the firstreactor to form a metathesis-reaction product; passing themetathesis-reaction product out of the first reactor in ametathesis-reaction product stream to a second reactor, the secondreactor comprising a cracking catalyst; at least partially cracking themetathesis-reaction product stream in the second reactor to form acracking-reaction product; passing the cracking-reaction product out ofthe second reactor in a cracking-reaction product stream comprisingbutene; and at least partially separating propylene from thecracking-reaction product stream to form a product stream comprisingpropylene, where: at least a portion of the butene in thecracking-reaction product stream is recycled by at least partiallyseparating butene from the cracking-reaction product stream to form arecycle stream comprising butene; and the recycle stream is mixed withthe metathesis-reaction product stream.
 11. The process of claim 10,where the first stream is a system inlet stream comprising at least 50wt. % butene.
 12. The process of claim 10, where the cracking-reactionproduct comprises at least 4 wt. % propylene.
 13. The process of claim10, where the product stream comprises at least 90 wt. % propylene. 14.The process of claim 10, where the recycle stream comprises at least 90wt. % of butane and butene.
 15. The process of claim 10, where: themetathesis catalyst comprises a mesoporous silica catalyst impregnatedwith metal oxide, where the mesoporous silica catalyst includes a poresize distribution of about 2.5 nm to about 40 nm and a total pore volumeof at least about 0.600 cm³/g; and the cracking catalyst comprises amordenite framework inverted (MFI) structured silica catalyst downstreamof the mesoporous silica catalyst, where the MFI structured silicacatalyst includes total acidity of 0.001 mmol/g to 0.1 mmol/g.
 16. Theprocess of claim 10, where the metathesis catalyst comprises anamorphous mesoporous silica foam impregnated with metal oxides, wherethe metathesis catalyst has a pore size distribution of at least 3 nm to40 nm and a total pore volume of at least 0.700 cm³/g.
 17. A system forproducing propylene as described in the method of claim 10.